LINKS:

IHTSDO-41 - Getting issue details... STATUS

Document review: JIRA IHTSDO-41(artf222643) Modelling of X in remission Documentation Review (Please note this review page is not public)

Amendment History

Review Timetable

© International Health Terminology Standards Development Organisation 2012. All rights reserved.
SNOMED CT® was originally created by the College of American Pathologists.
The International Release of SNOMED CT® is distributed by the International Health Terminology Standards Development Organisation (IHTSDO), and is subject to the IHTSDO's SNOMED CT® Affiliate Licence. Details of the SNOMED CT® Affiliate Licence may be found at http://www.ihtsdo.org/our-standards/licensing/.
No part of this document may be reproduced or transmitted in any form or by any means, or stored in any kind of retrieval system, except by an Affiliate of the IHTSDO in accordance with the SNOMED CT® Affiliate Licence. Any modification of this document (including without limitation the removal or modification of this notice) is prohibited without the express written permission of the IHTSDO.
Any copy of this document that is not obtained directly from the IHTSDO [or a Member of the IHTSDO] is not controlled by the IHTSDO, and may have been modified and may be out of date. Any recipient of this document who has received it by other means is encouraged to obtain a copy directly from the IHTSDO [or a Member of the IHTSDO. Details of the Members of the IHTSDO may be found at http://www.ihtsdo.org/members/].
Table of Contents
1 Glossary
1.1 Domain Terms
2 Introduction
2.1 Purpose
2.2 Audience and stakeholder domain
2.2.1 Input from stakeholders
2.2.2 Degree of consensus on the statement of problem
3 Statement of the problem or need
3.1 Summary of problem or need, as reported
3.2 Summary of requested solution
3.3 Statement of problem as understood
3.4 Detailed analysis of reported problem, including background
3.4.1 Determining the context in which "In remission" has a reproducible meaning
3.4.2 The Concept Model for representing "<disease> in remission"
3.4.3 Precoordination of "<disease> in remission" content
3.5 Subsidiary and interrelated problems
4 Risks / Benefits
4.1 Risks of not addressing the problem
4.2 Risks of addressing the problem
5 Requirements: criteria for success and completion
5.1 Criteria for success/completion
5.2 Strategic and/or specific operational use cases
5.2.1 Clear editorial policy development for "<disease> in remission" content
6 Solution Development
6.1 Initial Design
6.1.1 Outline of initial design
6.1.2 Significant design or implementation decisions / compromises
6.1.3 Evaluation of design
6.2 Iteration One
6.2.1 Outline of revised design
6.2.2 Revised modeling recommendations
6.2.3 Significant design or implementation decisions / compromises
6.2.4 Evaluation of revised design
7 Recommendation
7.1.1 Detailed design final specification
7.1.2 Iteration plan
8 Quality program criteria
8.1 Quality metrics
8.1.1 Quality metric 1
8.1.2 Quality metric 2
9 Project Resource Estimates
9.1 Projection of remaining overall project resource requirements
9.1.1 Expected project resource requirement category
9.1.2 Expected project impact and benefit
9.1.3 Indicative resource estimates for construction, transition and maintenance:
10 Appendix A - "<disease> in remission" concepts in the NLM CORE Problem List Subset
11 Appendix B – "<disease> in remission" concepts in SNOMED CT
12 Appendix C - Modeling inconsistencies to be addressed as part of the <disease> in remission project
12.1 Primitive "<Mental disorder> in remission" Concepts
12.2 Modeling to the nearest proximal primitive parent
13 Appendix D - <disease> status notes

Glossary

Domain Terms

Introduction

Purpose

The purpose of this project is to propose a Concept Model for "<disease> in remission" in SNOMED CT.

Audience and stakeholder domain

The audience for this document includes standards terminology leaders, implementers and users but is especially targeted at those stakeholders involved in the practice of oncology and mental health which are predominant domains for "<disease> in remission" content as well as authors of precoordinated SNOMED CT content and postcoordinated expressions following the recommended specification.

Input from stakeholders

As of the July 2015 International Release, there are 217 requests in SIRS related to disease in remission of which 162 were initiated since January 2013 and 79 remain active. Additionally, section 3.5 of this document on Subsidiary and Interrelated Problems addresses a number of related projects which indicate a user need to describe disease behaviors over time.

Degree of consensus on the statement of problem

There appears to be consensus on the need for a Concept Model to represent "<disease> in remission".
Areas where consensus is yet to be achieved include:

1. Whether "<disease> in remission" should be a subtype of |Disease (disorder)| or a subtype of 413350009 |Finding with explicit context (situation)|
2. The extent to which "<disease> in remission" content should be precoordinated in SNOMED CT.

Statement of the problem or need

Summary of problem or need, as reported

Description of the problem as per the Content Tracker artf222643 Modeling of "X in remission":

• Should "remissions" be modeled as "situations" instead of "disorders"
• If modeled as "situations" identify a template to be used for concept definitions

Summary of requested solution

A solution was not proposed with the initial request. However, in August 2011, the IHTSDO Chief Terminologist offered the following insight:
"A disease X in remission is not a separate kind of disease X, it is a status of the disease course.
In prior terminologies (SNOMED RT, CTV3) there was no situation hierarchy, so remission concepts were put in as subtype in the Is-a hierarchy of disease.
I would model disease in remission as a situation. Instead of modeling the fact that some disease manifestation is absent (exactly what must be absent, in order to achieve remission, varies from disease to disease), it seems it would be wise to assert a positive about disease phase. One modeling possibility is perhaps to activate the attribute "disease phase" as an attribute that can be used in the situation hierarchy, and model "disease phase" = "remission phase".
In other words, we would say that "schizophrenia in remission" is a situation, with associated-finding = schizophrenia, finding-context = known present, and disease-phase = remission phase."

Statement of problem as understood

A Concept Model is needed to represent "<disease> in remission".
Challenges include:

• Determining the context in which "In remission" has a meaning that can be consistently represented by the Concept Model and, in particular, whether the following two specific categories of remission can be modeled with one model.
  • Remission in response to treatment
  • Spontaneous remission as a natural disease process
• Developing the Concept Model for representing "<disease> in remission" including:
  • Determining whether "<disease> in remission" should be represented in the |Disease (disorder)| or |Finding with explicit context (situation)| hierarchy
  • Determining whether there is a reproducible boundary between disease stages, phases and courses and into which of those "In remission" falls.
  • Integrating the approach to modeling "<disease> in remission" with the approach for other similar disease characteristics (e.g., status, course, phase etc.)
• Determining the appropriate level of granularity (e.g., early remission, partial remission, complete remission) for precoordination of "<disease> in remission" content in SNOMED CT

Detailed analysis of reported problem, including background

Determining the context in which "In remission" has a reproducible meaning

A key issue in considering a model for "<disease> in remission" is whether there is a disease context in which "In remission" has a reproducible meaning that can be consistently represented with one Concept Model.
Examples of the varied clinical contexts in which remission is used include:

1. Remission as part of the natural history of a disease (e.g., spontaneous remission)
2. Remission as a response to treatment of a disease
3. Remission in disorders with very objective measures of disease (e.g., signs observed on examination or by testing)
4. Remission in disorders with more subjective measures of disease (e.g., some behaviors and mental health disorders/findings)

The SNOMED CT concepts qualified with "in remission" and the related requests in SIRS are varied. However, two common categories of content qualified with "in remission" include:

• Chronic, generally progressive diseases which may or may not be curable (e.g., malignancies)
• Behavior and mental health disorders which may or may not be progressive

Examples of "in remission" as a modifier for findings/disorders
Concepts in bold are already in SNOMED CT. Concepts in italics represent SIRS requests not yet added as of the July 2015 release (which generally have their origins in ICD codes):

• • Ulcerative colitis in remission (disorder)
  • Leukemia in remission (disorder)
  • Eating disorder in remission (disorder)
  • Schizophrenia in remission (disorder)
  • Cocaine dependence in remission (disorder)
  • Postpartum major depression in remission (disorder)
  • Peer problems in remission (finding)
  • Relationship problems in remission (finding)
  • Codependency in remission (finding)
  • Bereavement in remission (finding)
  • Alcohol dependence in early full remission (disorder)
  • Compulsive gambling in remission (disorder)
  • Age related cognitive decline in remission (disorder)

Definition of Remission

Specific criteria and definitions for remission may vary by disease or specialty. Most definitions include some variation of Dorland's general definition:

1. Diminution or abatement of symptoms of a disease
2. The period during which such diminution occurs

The first definition above describes the disease state, whereas the second describes the period of time during which the state occurs.
Other definitions for remission are increasingly granular. For example:

• Diminution or abatement of signs and symptoms of a disease
• Diminution or abatement of sign and symptoms of chronic or malignant diseases
• Diminution or abatement of sign and symptoms of chronic or malignant diseases in response to treatment
• Diminution or abatement of sign and symptoms of incurable, chronic or malignant diseases in response to treatment

Essentially all definitions for remission include some type of lessening of symptoms. While terms like "diminution", and "abatement" generally imply a change in the nature of the disease, they also insinuate that the disease is ongoing. Remission is not a cure, it is temporary. It can be partial or complete and can occur spontaneously or as a response to treatment.
For the purpose of trying to move forward with this model, it is it is suggested that SNOMED CT use the following definitions:
In remission: the period in the course of a disease/condition during which there is temporary lessening or abatement of signs and/or symptoms of the disease
This definition does not constrain the meaning of remission with respect to how the remission was achieved (spontaneous or in response to treatment).
In partial remission the period in the course of a disease/condition during which the signs and/or symptoms of the disease have temporarily lessened but remain present/detectable to some degree
In complete remission the period in the course of a disease/condition during which the signs and/or symptoms of the disease are temporarily no longer present/detectable. Complete remission is not a cure.
In spontaneous remission the period in the course of a disease/condition during which there is unexpected (in the absence of treatment) lessening or abatement of the signs and/or symptoms of the disease. In some disease contexts, this is also called spontaneous regression.
Remission is followed by disease relapse or recurrence which are also terms that may have different meanings in different contexts. Defining the meaning of relapse and recurrence is not part of this project. However, they are considered here because the model for "<disease> in remission" should logically extend to other phases which are also part of the natural course of a disease. Although some of the other disease phases (e.g., prodrome, convalescence, incubation etc.) are minimally used as disease descriptors in SNOMED CT, recurrence and relapse are used for several hundred concepts. For this reason, the definitions for relapse and recurrence, although not being suggested as part of this project, are presented here. In particular, this creates a significant dependency on the outcome of the project related to artf6221: Recurrent malignant neoplasm.
Relapse (as a phase) the period in the course of a disease/condition that follows remission (or an interval of improvement) during which there is a reappearance of the signs and/or symptoms of the disease
Recurrence of disease and recurrent disease are terms with significant ambiguity in clinical use. Two possible uses are provided.
Recurrence of disease the return of signs and/or symptoms of a disease/condition after remission.
Recurrent disease is often used to refer to an entirely new episode (e.g., a separate disease) of a disease/condition which the patient has previously experienced (e.g., |Recurrent miscarriage (disorder)|, |Recurrent bacterial cystitis (disorder)|, |Recurrent pneumonia (disorder)|).
However, for malignancies, the return of the original disease can be called a recurrence (e.g., |Local recurrence of malignant tumor of colon (disorder)|). In some contexts, this may also be called recurrent malignant disease (e.g., recurrent multiple myeloma).
Determining when "recurrence of <disease>" and "recurrent <disease>" represent a disease phase that follows remission in the course of a single disease as opposed to a disease that represents an entirely new episode of a previously experienced disease can be challenging (see artf6221: Recurrent malignant neoplasm).
This project has a general dependency on many of the projects listed in Section 3.5 which address modeling of disease courses and phases. For example, the model for |Chronic disease (disorder)| in SNOMED CT is also quite relevant because, often, remission is a phase in a chronic disease. Therefore, consideration should also be given to how the model for remission will be integrated with the model for chronic disease. (See project related to artf222304 & artf222305 Review "Chronic respiratory disease in perinatal period" as a chronic condition & Review "Lichen simplex chronicus" as a chronic condition). The dependencies on other projects will be further addressed in Section 3.4.2 on the Concept Model for representing "<disease> in remission".

The Concept Model for representing "<disease> in remission"

The concept model for "<disease> in remission" requires:

• Determining whether "<disease> in remission" should be represented in the |Disease (disorder)| or |Finding with explicit context (situation)| hierarchy
• Determining whether there is a reproducible boundary between disease courses, phases and stages and into which of those "remission" falls
• Integrating the model for "<disease> in remission" with the approach for modeling other similar qualifiers that describe disease status/behavior over time (e.g., recurrence of disease)

Representation of "<disease> in remission" as a |Disease (disorder)| or a |Finding with explicit context (situation)|

The issue of whether "<disease> in remission" should be represented in the |Disease (disorder)| hierarchy or the |Finding with explicit context (situation)| hierarchy requires consideration of how "<disease> in remission" has been modeled in SNOMED historically as well as how similar content is being modeled or will be modeled going forward.
Since 2004, SNOMED CT editorial policy guidance on the |Disease (disorder)| hierarchy has provided the following three criteria related to disorders (from the July 2015 SNOMED CT Editorial Guide Section 6.1.1.1 Disorders):

1. Disorders necessarily are abnormal.
2. They have temporal persistence, with the (at least theoretical) possibility of their manifestations being treated, in remission, or quiescent even though the disorder itself still present.
3. They necessarily have an underlying pathological process

Criteria #2 aligns with the proposed definition of "In remission" in that it specifically addresses the idea that a disorder is still considered to be present even when it is in remission. It also establishes that that the existing approach has been to represent "<disease> in remission" in the |Disease (disorder)| hierarchy.

Representation of "<disease> in remission" as a |Finding with explicit context (situation)|

One suggestion on the Content Tracker proposes modeling "<disease> in remission" as a situation (in the |Finding with explicit context (situation)| hierarchy). From the Content Tracker on 10/18/2011:
Instead of modeling the fact that some disease manifestation is absent (exactly what must be absent, in order to achieve remission, varies from disease to disease), it seems it would be wise to assert a positive about disease phase. One modeling possibility is perhaps to activate the attribute "disease phase" as an attribute that can be used in the situation hierarchy, and model "disease phase" = "remission phase".
The above approach for representing "<disease> in remission" as a situation proposes making 278174000 |Disease phase (attribute)| an approved attribute with a range of 303105007 |Disease phases (qualifier value)|.
Following the above proposal, "<Disease X> in remission" might be modeled:

=== |Clinical finding present (situation)| :

            { |Associated finding (attribute)| =  |Disease X (disorder)|,

               |Temporal context (attribute)| = |Current or specified time (qualifier value)|,

               |Finding context (attribute)| = |Known present (qualifier value)|,

               |Subject relationship context (attribute)| = |Subject of record (person)|

 |Disease phase (attribute)| = Remission phase (qualifier value) }

The July 2015 value set for |Disease phases (qualifier value)| includes:

• Accelerated phase (qualifier value)
• Acute phase (qualifier value)
• Chronic phase (qualifier value)
•  Convalescent phase (qualifier value) 
• Prodromal phase (qualifier value) 
• Relapse phase (qualifier value) 
• Remission phase (qualifier value) 
  • In complete remission (qualifier value) 
  • In partial remission (qualifier value) 
• Transformed phase (qualifier value)

Potential issues related to |Disease phases (qualifier value)| and the proposal to make |Disease phase (attribute)| an approved attribute include:

1. The set of values for | Disease phases (qualifier value) | may be relative to the diseases that they qualify. For example, the phases for infectious diseases are different than the phases for malignant diseases. Therefore, determining the value set and the hierarchical ranking of the values may be challenging. 
2. While spontaneous remission is a naturally occurring disease phase, remission in response to treatment (the more likely meaning when applied to malignant diseases) is actually a treatment response rather than a naturally occurring disease phase. (The same may be true for |Convalescent phase| in some cases.)
3.  If | Disease phase (attribute) | is made an approved attribute, a review of existing SNOMED CT content indicates that several of the values in the | Disease phases (qualifier value) | value set would only apply to few (if any) existing disease concepts. For example, as of the July 2015 Release, there are only 2 disorders in SNOMED CT concept with "prodromal" in their FSNs.
4. The values in the set which might have a broader use include:

• • Acute phase (qualifier value)
  • Chronic phase (qualifier value)
  • Relapse phase (qualifier value)
  • Remission phase (qualifier value)

These values overlap to some degree with values in the |Courses (qualifier value)| hierarchy and this overlap may lead to further inconsistency in concept definitions.

Examples:

• |Acute phase (qualifier value)| versus |Sudden onset AND short duration (qualifier value)| This might contribute to the existing ambiguity as to the meaning and model of Acute <disease> (as described in section 3.4.3.1) 

• |Relapse phase (qualifier value)| versus |Relapsing course (qualifier value)| |Relapse phase (qualifier value)| and |Relapsing course (qualifier value)| have dependencies on the model being developed for “recurrence of <disease>”.

5. Modeling of similar “disease status” content

Earlier proposals that suggested representing "<disease> in remission" as a situation modeled with |Disease phase (attribute)| suggested that other disease status concepts should also be situations. This would increase the scope of the task significantly. Recommended content to be moved to situations in a document titled "Event-condition-episode_notes-ks.doc" (see Appendix D - <disease> status notes) included:

• In remission, in relapse, in partial/complete remission -> disease phase (attribute)
• In control, not in control, in poor control, in good control -> NEW attribute needed.
• Disease phase (acute phase, convalescent phase, etc.) -> disease phase (attribute)
• Severity (mild, moderate, severe) -> severity (attribute)
• Stage -> staging of disease (attribute)
• Episodicity -> episodicity (attribute)

Many of the issues related to |Disease phases (qualifier value)| are similar to issues that impact the URU of |Clinical course (attribute)| and its value set |Courses (qualifier value)| which will be discussed in more detail in subsequent sections.

Representation of "<disease> in remission" as a |Disease (disorder)|

Representing "<disease> in remission" in the |Disease (disorder)| hierarchy might be an alternative solution to representing "<disease> in remission" as a |Finding with explicit context (situation)| for the following reasons:

1. In the |Disease (disorder)| hierarchy, "<disease > in remission" could also be modeled using either |Disease phase (attribute)| or |Clinical course (attribute)| with the value "In remission". Other options might include assigning stated high-level "Disease in remission" grouper concepts.
2.  Several hundred "<disease> in remission" concepts are already in the |Disease (disorder)| hierarchy where "<Disease X> in remission" is generally a subtype of "Disease X". 
3. Concepts representing disease characteristics similar to "In remission" are already largely represented in the |Disease| hierarchy.
   1. These include; disease course (e.g., chronic, relapsing), disease control status (e.g., poor, progressive, refractory, intractable, active), and disease severity and episodicity
   2. Similar content continues to be added to the |Disease| hierarchy (e.g., |Severe persistent asthma controlled co-occurrent with allergic rhinitis (disorder)|) 
4. If "<disease> in remission" is represented in the |Finding with explicit context (situation)| hierarchy, determining which of the similar, existing disease course/process/status/phase concepts should also be moved to the |Finding with explicit context (situation)| hierarchy would be an arduous (if not nearly impossible) task that is unlikely to be completed in the near future. In the interim, a lack of consistency in the modeling of similar content could present a barrier to implementation.

For example, changing |Single manic episode in full remission (disorder)| to a |Situation with explicit context| while leaving its similar siblings as subtypes of |Manic disorder, single episode (disorder)| will not facilitate implementation.

5. "<disease> in remission" content is somewhat similar to content in the |Evaluation finding (finding)| hierarchy which represents evaluation results.

1. 1. Concepts that qualify diseases based on their behaviors (e.g., metastatic, recurrent, relapsing, refractory, controlled, in remission) are often findings about the disease rather than different types of the disease.
   2. The determination that a disease is in remission is based on specific criteria that often involve symptoms and signs (based on imaging, laboratory testing etc.). Rather than being an evaluation result related to a specific test, it is an evaluation result about a disease phase based on a number of observations/tests.
   3. It is not currently being proposed to make "<disease> in remission" concepts subtypes of |Evaluation finding (finding)|. However, existing editorial policy suggests that evaluation findings should remain in the |Clinical finding| hierarchy rather than in the |Situation with explicit context| hierarchy. It is reasonable that "<disease> in remission" concepts should also remain in the |Clinical finding| hierarchy albeit as subtypes of |Disease|.
   4. Keeping "<disease> in remission" concepts in the |Clinical finding| hierarchy also aligns with the clinical life phase interpretation of disease as proposed by the Event, Condition and Episode Model Project.

Determining whether there is a reproducible boundary between disease courses, phases and stages and into which of those "<disease> in remission" falls

An additional consideration in the model for "<disease> in remission" is whether to represent remission as part of the disease course, as a disease phase or as a disease stage.
Some historical indicators of previous difficulties in determining the appropriate attribute and hierarchy for the concept model for "<disease> in remission" include:

1. 70919002 |In remission (qualifier value)| was once an allowed value for |Severity (attribute)| but it was later retired as |Ambiguous concept| with |MAY BE A| relationships to |Remission phase (qualifier value)| and |Patient in remission (qualifier value)|).
2. 110279003 |Inactive disease following therapy (finding)| is a concept in SNOMED CT.
   1. This is a similar concept to "<disease> in remission in response to treatment"
   2. |Inactive disease following therapy (finding)| previously had a description “Disease in remission” which was retired (possibly because not all remissions follow therapy).

   3. |Inactive disease following therapy (finding)| is currently a subtype of |General finding of observation of patient (finding)| but it was formerly a |Context-dependent finding (finding)| which is now retired and a synonym for |Finding with explicit context (situation)|. Thus, the debate as to whether this type of concept should be a finding or a situation is not new.

An initial reasonable approach might be to continue to model "<disease> in remission" concepts in the |Disease| hierarchy using |Disease phase (attribute)| to model "In remission" as a phase in the course of a disease. However, because definitions for disease phases/stages may be relative to the disease they qualify, it may be difficult to determine the value set for |Disease phase| and a hierarchical order for the values that is consistent for all diseases.
Examples:

• For infectious diseases, the stage of subclinical disease is usually called the incubation period 

• For chronic diseases, the stage of subclinical disease is usually called the {_}latency period_

• For alcoholism, the first phase is often called the pre-alcoholic phase.

Additionally, this may contribute to inconsistency in modeling and confusion between |Clinical course (attribute)| and |Disease phase (attribute)|. The boundaries between a disease course and the processes that make up the disease course (e.g., phases, stages, and patterns) can be difficult to distinguish. "Stage" and "phase" are used interchangeably in some contexts, while at other times they have distinct meanings. For example, the CDC depicts a "Natural History of Disease Timeline" (below) in which the "Stage of Recovery" overlaps somewhat with disease phases in SNOMED CT (e.g., the concept |Convalescent phase (qualifier value)| in the |Disease phases (qualifier value)| hierarchy).

Source: Centers for Disease Control and Prevention. Principles of epidemiology, 2nd ed.
Atlanta: U.S. Department of Health and Human Services;1992.
In general, most definitions for disease phase refer to disease behavior during a particular period in the history of a disease (the disease course).
Definitions for disease course, which is often referred to as the "natural history of a disease", also vary as demonstrated in the definitions provided below. In general, the most consistent aspect of the definition for disease course is that it describes disease behavior over the entire history of the disease:
The natural history of disease is the course a disease takes in individual people from its pathological{_} onset ("inception") until its eventual resolution through complete recovery or death.
An important, additional consideration is that disease courses and phases generally include the restriction that they relate to naturally occurring events in the history of a disease. The CDC "Principles of Epidemiology in Public Health Practice" specifically states:
_Natural history of disease refers to the progression of a disease process in an individual over time, in the absence of treatment.
Thus, while spontaneous remission may be part of the natural history of a disease, remission in response to treatment is not truly a natural disease phase or part of the natural course of a disease. Responses to treatment are also handled in somewhat inconsistently in SNOMED, sometimes they are findings and at other times disorders.
Examples:
444110003 |Type II diabetes mellitus well controlled (finding)|
300996004 |Controlled atrial fibrillation (disorder)|
1107004 |Early latent syphilis, positive serology, negative cerebrospinal fluid, with relapse after treatment (disorder)|
704369007 |Fatigue due to treatment (finding)|
234365008 |Thiamine-responsive macrocytosis (disorder)|
Ideally, the concept model should represent "spontaneous remission" and "remission in response to treatment" in a consistent manner while allowing for the distinction between the two as well as for the more general representation of "in remission".
The Ontology for General Medical Science (OGMS) also provides some definitions related to disease, disease course, remission and relapse which may be useful.
Disorder - A material entity which is clinically abnormal and part of an extended organism. Disorders are the physical basis of disease.
Disease - A disposition to undergo pathological processes that exists in an organism because of one or more disorders of that organism.
Disease course - The totality of the processes through which a given disease instance is realized.
Remission - A part of a disease course that includes a temporary convalescence.
Relapse - _A part of a disease course that occurs after an incomplete remission and that is similar to earlier parts of the disease course.
The paper +Toward an Ontological Treatment of Disease and Diagnosis(one basis for OGMS) and Barry Smith's presentation "Disease and Other Natural Clinical Kinds", further present a disease as a continuant which is dependent on an organism (the independent continuant) which is the bearer of the disease. The disease course is considered to be a process that is an occurrent (e.g., has temporal components) but is also the sum of other occurrents (e.g., patterns, qualities, phases of the disease course).

Taken from (http://www.slideshare.net/BarrySmith3/berlin-bfo-anddisease2012)
In Barry Smith's presentation, a Disorder is present as part of the Etiological Process of a Disease but the actual Disease Course is not initiated until signs/symptoms are present.

Even in this depiction, it appears that spontaneous remission would be part of the Disease Course whereas remission in response to treatment would be part of the Therapeutic Response. Thus, in OGMS, it is also not entirely clear where the more general representation of "<disease> in remission" would fit in the "Big Picture".
The difficulty in clearly separating the modeling of the overall clinical course of a disease from its phases (temporal components) is also apparent in the SNOMED CT editorial guidance on 263502005 |Clinical course (attribute)| (from the July 2015 Editorial Guide Section 6.1.2.8 CLINICAL COURSE):
This attribute is used to represent both the course and onset of a disease. Many conditions with an acute (sudden) onset also have an acute (short duration) course. Few diseases with a chronic (long - term) course would need to have their onset sub-divided into rapid or gradual subtypes, and thus there is no clear need for separating the rapidity of onset from the duration of a disease; based on testing by implementers and modelers, a single attribute with values that combine these meanings has clearly been more reproducible and useful than two attributes that attempt to separate the meanings.
Thus, |Clinical course (attribute)| is already overloaded in that it is used to represent a disease course (e.g. |Clinical course with short duration (qualifier value)|) and a disease phase (e.g., |Acute onset (qualifier value)|, |Gradual onset (qualifier value)| etc.).
The issue of disease course is further complicated by some overlap between |Clinical course (attribute)| and |Severity (attribute)| which is also described in the Editorial Guide Section 6.1.2.8 for |Clinical course|:
The word acute has more than one meaning, and the meanings are often overlapping or unclear. The word acute may imply rapid onset, short duration, or high severity; in some circumstances it might be used to mean all of these. For morphological terms it may also imply the kind of morphology associated with the speed of onset. | Acute inflammation (morphologic abnormality) | does not necessarily have CLINICAL COURSE | Sudden onset AND/OR short duration |, but rather implies polymorphonuclear infiltration; likewise | Chronic inflammation (morphologic abnormality) | implies mononuclear cell infiltration, not necessarily a chronic course, although inflammation with a chronic course is highly correlated with a lymphocytic infiltration.
The above explanation acknowledges the possible ambiguity in the meaning of "Acute <disease>" where "acute" may describe the disease course, onset, or severity and may also have an additional meaning in relation to onset that includes a morphological change (inflammation). Similarly, in addition to considering whether to model "in remission" is a disease course or a disease phase, the history of 70919002 |In remission (qualifier value)| discussed in Section 3.4.3.3 of this document indicates that it was also once a value for |Severity (attribute)|.

Integrating the approach to modeling "<disease> in remission" with the approach for other disease qualifiers that describe disease behavior

For modeling consistency and taxonomies that support user implementation, the concept model for "<disease> in remission" should consider the model for other disease behaviors/statuses over time (e.g., onset of disease, recurrence of disease) some of which are currently modeled with |Clinical Course|). A reasonable approach at this time might be a model that works within the existing infrastructure with the already approved attribute |Clinical Course|. At a later time, if a solution and resources become available to retire concepts precoordinated with disease behavior (e.g., course, status, phase) and to create new concepts in the |Situation with explicit context| hierarchy, new attributes and extensive changes to the concept model will be required and a new model for "<disease> in remission" will likely be integrated with that project.
Note: After feedback on this project, this approach was changed in "Section 6.2 Iteration One". The revised approach in Section 6.2 still allows for a model that can most likely be adapted to a broader model for other disease behaviors/statuses if one is developed. This is true particularly because the feedback provided generally concurred that this content should remain in the |Disease| hierarchy rather than in the |Situation| hierarchy.

Precoordination of "<disease> in remission" content

Artifact artf221579 : <disease> in remission (disorder) currently has a status of "Temporarily not allowed" on the IHTSDO Pre-coordination roadmap patterns Tracker. The IHTSDO will decide the degree to which "<disease> in remission" content should be precoordinated. However, the potential for combinatorial explosion for "<disease> in remission" concepts, particularly in the area of mental health, is fairly easy to foresee.
For example, |Mental disorder (disorder)| has nearly 1300 subtypes many of which could be qualified by permutations of "in remission".
Example:
Although the first-level subhierarchy of |Mood disorder (disorder)| includes only two "in remission" concepts, virtually all of the mood disorders and their subtypes can be in remission (e.g., full, partial, early full, early partial, sustained full, sustained partial, etc.).

Submissions in SIRS (not yet added as of the July 2015 Release) further illustrate the permutations of "<disease> in remission" that are being requested.
Examples:
Alcohol abuse in sustained partial remission (disorder)
Alcohol abuse in early partial remission (disorder)

Subsidiary and interrelated problems

Several content projects and one precoordination roadmap pattern address modeling issues related to disease characteristics similar to "in remission" which are currently largely represented using |Clinical course (attribute)| and are interrelated with the model for "<disease> in remission". In particular, the concept models for "<disease> in remission" and "<disease> recurrence/relapse" are highly interdependent.

A project is needed to define the concept model for recurrent malignant disorders, i.e. “Recurrent malignant neoplasm 

of X” type concepts. These would be a kind of Recurrent disease.  A recurrence can be local at the primary site or a 

metastasis. 

1480 3004|Transitory (qualifier value)| Asserted SubClassOf 424124008| Sudden onset AND/OR short duration (qualifier 

value)|

Is |20322005|Chronic respiratory disease in perinatal period| properly a chronic condition?

“Lichen simplex chronicus” needs authoritative confirmation as to whether or not it is a chronic disease.

Risks / Benefits

As of the July 2015 release, there are 150 "<disease> in remission" concepts in SNOMED CT and 79 pending requests in SIRS which indicate a user requirement for "<disease> in remission" content. There are also 34 "<disease> in remission" concepts in the 2015 NLM CORE Problem List Subset of SNOMED CT^® (see Appendix A - "<disease> in remission" concepts in the NLM CORE Problem List Subset). The objective is to address the existing content and the backlog of requests in a manner that benefits content authors as well as user implementations.

Risks of not addressing the problem

1. The "<disease> in remission" pattern has been on hold for several years under the precoordination roadmap Artifact artf221579 : <disease> in remission (disorder). The NLM CORE Problem List Subset and SIRS requests are an indication of users' need for this content. A policy decision with respect to inclusion of this content and editorial guidance on how to model it is needed to assist the IHTSDO content team and NRCs in managing the requests efficiently. The ability to sufficiently define some "<disease> in remission" concepts will also assist classification, retrieval and equivalency detection. Additionally, the likelihood of interoperability decreases if users postcoordinate this content in the absence of a model. 
2. Implementing the model currently proposed on the Content Tracker in which "<disease> in remission" content is modeled as a |Situation with explicit context| without addressing the large number of similar disease behavior concepts currently in the |Disease| hierarchy will result in inconsistent approaches to similar content in SNOMED CT which may negatively impact user implementation.

Risks of addressing the problem

1. Expert resources will require adequate time to model the existing and requested "<disease> in remission" concepts to ensure that remodeling content does not result in loss of correct parents or subtypes. For example, there is some risk that when remodeling content to the nearest proximal primitive and removing some currently stated parents which are sufficiently defined, that the prior parents will not return after classification due to modeling inconsistencies outside the scope of this project (see example in Appendix C - Modeling inconsistencies to be addressed as part of the <disease> in remission project.) 
2. If a concept model for "<disease> in remission" results in an end to the temporary ban on precoordination of this content, requests for "<disease> in remission" content may increase. 
3. The concept for model "<disease> in remission" should align with the concept model for similar content and is, therefore, highly dependent on models being developed for similar "<disease> behavior" content. This creates a risk that if, at a future time, an overarching editorial policy is developed for "<disease> behavior" type content, the "<disease> in remission" content might need to be modeled again. 
4. "<disease> in remission" is vague. In clinical contexts, it is likely being used to represent "<disease> in remission in response to treatment".

Regardless of whether the model adopted ultimately uses an attribute and the new value set initially proposed in this document or whether the model uses the second approach suggested in "Section 6.2 Iteration One", there will be a model for precoordination of "<disease> in remission in response to treatment" which might result in a shift in meaning for some "<disease> in remission" concepts which may have actually been used in a record to represent "<disease> in remission in response to treatment". (This is similar to what happened with "appendectomy" which implicitly meant "open appendectomy" until a "closed appendectomy" became possible. After closed (laparoscopic) appendectomies were introduced, the meaning of "appendectomy" shifted from representing "open appendectomy" to representing the more general supertype of both "open appendectomy" and "closed appendectomy".)

Requirements: criteria for success and completion

Criteria for success/completion

The criteria for successful completion of this project include:

1. Providing a concept model for "<disease> in remission" that:
   1. Allows consistent precoordination and/or postcoordination for the more common "<disease> in remission" patterns
   2. Ensures proper classification results and equivalency detection
   3. Is consistent with, or can be adapted to, the concept model for similar disease behavior/status content to facilitate user understanding and implementation
2. Modeling existing "<disease> in remission" in accordance with editorial policy
3. Providing inclusion criteria guidance to support submitters and editors in determining appropriate content to submit/add to SNOMED CT

Strategic and/or specific operational use cases

Clear editorial policy development for "<disease> in remission" content

Editorial policy guidance and inclusion criteria and for the Concept Model for "<disease> in remission" content to will help to ensure the integrity of SNOMED CT content in order to meet users' expectations and implementation needs.

Fit with IHTSDO strategy

A sound and valued primary product [SNOMED CT] - A model that facilitates consistent precoordination and/or postcoordination of "<disease> in remission" concepts helps to ensure a quality product.
Make it easier to use SNOMED CT for priority use cases - Based on SIRS requests and NLM CORE Problem List subset usage data, there is a user need for "<disease> in remission" content particularly in the areas of mental disorders and malignancies. Facilitating semantic representation will improve the accurate collection and sharing of this content.

Solution Development

Initial Design

The most significant outcome of this analysis is the conclusion that a concept model for "<disease> in remission" should be part of a single project that provides a unified model for qualifying disease behaviors/statuses (e.g., disease activity, response to treatment, course, severity, extent, etc.). In the absence of an overarching model, a model that works within the existing model is being suggested to provide a means to sufficiently define the majority of the existing "<disease> in remission" content until an overarching model for "<disease> behavior" content is developed.

Outline of initial design

Based on the analysis outlined in Section 3.4, the proposed approach for the concept model for "<disease> in remission" is to use |Clinical Course (attribute)| and to add an "In remission" value set to |Courses (qualifier value)|.
NOTE: After feedback, this approach presented in Section 6.1 was revised in Section 6.2 - Iteration One. Although many of the issues discussed in this section also apply to the new model proposed in Section 6.2, the new model shifts the representation of the "in remission" characteristic from attribute value pairs to high-level "Disease in <remission>" grouper concepts as stated parents. This section (6.1) has been left largely intact as parts of it might still be adapted and added to the "Disease in remission" model in the event that an overarching model that designates attributes for other similar disease behaviors is developed. For the final proposed model, please skip to Section 6.2 - Iteration One.

Modeling "<Disease> in remission" with the |Clinical Course| attribute

Analysis of the |Clinical Course| attribute and the concepts in the |Courses (qualifier value)| value set indicates that there are a number of areas where the current concept model for |Clinical Course| fails URU criteria for acute and chronic diseases.

Issues related to |Clinical Course (attribute)| and the |Courses (qualifier value)| value set include:

• Ambiguity in the meaning/modeling of "disease course" using |Clinical Course|

Examples:

• • There is some overloading of the attribute
    • Used to model the entire course (e.g., chronic)
    • Used to model parts of the course (e.g., onset)
  • Ambiguity in the meaning and model for Acute <disease>

• Diseases with a course (e.g., chronic) that is not explicitly specified in the FSN are generally not modeled using |Clinical Course|

Examples:

• • |Huntington's chorea (disorder)|
  • |Systemic sclerosis (disorder)|  
  • Many Granulomatous diseases 

• Values in the |Courses| value set may be relative to the diseases that they qualify

Examples:

• • Recurrence - has different meanings in different contexts
    • For some diseases it may mean that the disease was always present in a subclinical state (some malignancies)
    • For other diseases may mean an entirely separate episode of the disease (e.g., recurrent pneumonia) 
  • Chronic - has different meanings in different contexts
    • Chronic cough is eight weeks or longer
    • Chronic depression is 2 years or longer 
  • Chronic active hepatitis (disorder) has synonym "CAH - Chronic aggressive hepatitis" in which case the two values below overlap but they may not necessarily overlap for other disorders. 
    • Chronic active (qualifier value)
    • Chronic aggressive (qualifier value)

• Values that combine clinical course and morphology 

Examples:

• |Chronic miliary (qualifier value)|
• |Chronic granulomatous (qualifier value)| 
•  Values that negate rather than assert

Example

• |Non-progressive (qualifier value)| - this could be applied to virtually every disease with a course that is not progressive

Proposed model for "<disease> in remission"

In spite of the limitations described for |Clinical Course|, it still appears that the most reasonable interim approach would be to model "<disease> in remission" with the |Clinical Course| attribute and to add "In Remission" values as subtypes of |Courses (qualifier value)|.

Example expression of a sufficiently defined, stated concept definition using the proposed model:

|Cyclothymia in remission (disorder)|

=== |Cyclothymia (disorder)| :

|Clinical course (attribute)| = |In remission (qualifier value)|

Advantages to this approach at this time include:

1. "<disease> in remission" will remain in the |Disease| hierarchy with other similar content.
2. "In remission" will be in the |Courses| value set with other values that represent disease activity (e.g., |Chronic active|, |Recurrent|).
3. Although the |Disease phase (attribute)| could be approved as an attribute for the |Clinical finding| hierarchy and could also be used to model "<disease> in remission", this may contribute to inconsistency in modeling due to overlap between values in the |Disease phases| and Courses| value sets (previously discussed in Section 3.4.2.1).
4. "<disease> in remission" content should be impacted less by the URU issues associated with |Clinical Course| than some other content because:
   1. Unlike chronicity, and some of the other values in |Courses|, when a finding or disorder is in remission, it is usually explicitly asserted in the concept's FSN.
   2. The values in the "In remission" value set are more straightforward to rank against one another than many of the other nominally ranked qualifier values (e.g., none, absent, nil).
5. For the limited number of concepts that require a disease course and an "In remission" status, two ungrouped |Clinical course| attributes with a value for disease course and a value for remission status, while not optimal, should not be disruptive to classification.

Modeling Recommendations

Add "In remission" concepts to the value set for |Courses (qualifier value)|

The suggested "In remission" value set (below) covers the more common "In remission" permutations. All values would not necessarily need to be used in precoordination. However, they would allow modeling of the more common distinctions in remission types (e.g., spontaneous, after treatment, partial or complete). Even if not used fully in the International Release, this increased expressivity could be useful in postcoordination particularly in settings which analyze remission in response to treatment.

Proposed new values

Courses (qualifier value)

In remission (qualifier value)

In partial remission (qualifier value)

        In spontaneous partial remission (qualifier value)

In partial remission in response to treatment (qualifier value)

In complete remission (qualifier value) (Synonym: In full remission)

         In spontaneous complete remission (qualifier value)

In complete remission in response to treatment  (qualifier value)

In spontaneous remission (qualifier value)

In spontaneous partial remission (qualifier value)

In spontaneous complete remission (qualifier value)

In remission in response to treatment (qualifier value)

In partial remission in response to treatment (qualifier value)

In complete remission in response to treatment (qualifier value)

|Clinical course (attribute)| is also used to model acute and chronic disease courses. Therefore, to support classification and the ability to represent acute and chronic disease courses in remission with a single attribute value pair, a more extensive value set that combines course (acute or chronic) with remission values was considered. Below are examples of a few more granular subtypes of In remission (qualifier value) that combine chronic course and remission status into a single value. Similar values could be added for combinations of acute course and remission.

Examples of more granular “in remission” qualifier values that could be added if requested:

Chronic disease course in remission (also a subtype of |Chronic (qualifier value)|)

Chronic disease course in partial remission

Chronic disease course in complete remission

Chronic disease course in spontaneous remission

Chronic disease course in remission in response to treatment

If there was a significant amount of precoordinated content in SNOMED CT that combined disease course and remission status, these additional, more granular values such as the five shown above might be beneficial. However, as of the July 2015 Release, there are only 4 “chronic <disease> in remission” concepts and 11 “acute <disease> in remission” concepts in SNOMED CT most of which would still be able to be sufficiently defined on the basis on their |Associated morphology| and a |Clinical Course| = In remission (qualifier value). Thus, a more extensive value set than the 9 proposed new values does not seem not warranted at this time.

Address the three existing subtypes of | Disease phases (qualifier value) | which correspond to values in the proposed “In remission” value set.

• Remission phase (qualifier value)
• In complete remission (qualifier value)
• In partial remission (qualifier value)

These three values are not currently in the allowable range for any approved attribute. They are presumably the value set for 278174000 |Disease phase (attribute)| which is an |Unapproved attribute (attribute)|. They are not yet used in SNOMED CT so (per editorial guidance) they should not be used in postcoordination. Thus, it may be acceptable to:

1. Move |In complete remission (qualifier value)| and |In partial remission (qualifier value)| and make them two of the proposed subtypes for the new |In remission (qualifier value)| concept.
2. Retire |Remission phase (qualifier value)| as |Reason not stated| to avoid confusion with the new |In remission (qualifier value)| concept.

Add new Disorder in remission (disorder) grouper concepts

Add the following new grouper concepts and sufficiently define them with |Clinical Course| and values from the |In remission (qualifier value)| hierarchy.

• Disorder in remission (disorder)
  • Disorder in remission after treatment (disorder)
  • Disorder in spontaneous remission (disorder)
  • Disorder in partial remission (disorder)
  • Disorder in complete remission (disorder)

Corresponding "Disease in <remission>" synonyms can be added for the 5 new concepts.
Example expression of a sufficiently defined, stated concept definition using the model:

=== |Disease (disorder)| :

|Clinical course (attribute)| = |In remission (qualifier value)|

If needed, additional, sufficiently defined subtypes of Disorder in remission (disorder) can be added as additional groupers to correspond with each of the values the |In remission (qualifier value)| hierarchy.

Model existing "<disease> in remission" concepts

The list of "<disease> in remission" concepts as of the July 2015 Release is provided in Appendix B.

Add 263502005 |Clinical course (attribute)| to "<disease> in remission" concepts

For existing concepts, add 263502005 |Clinical course (attribute)| with the appropriate "In remission" value in the stated view in accordance with current editorial guidance on modeling (to model to the nearest proximal primitive parent). Many concepts will be able to be sufficiently defined.

Examples - Expressions of stated concept definitions:

1. |Undifferentiated schizophrenia in remission (disorder)|

=== |Undifferentiated schizophrenia (disorder)| :

                        |Clinical course (attribute)| = |In remission| (qualifier value)|

1. |Major depression, single episode, in complete remission (disorder)|

=== |Major depression, single episode (disorder)|

|Clinical course (attribute)| = |In complete remission (qualifier value)|

1. 427141003 |Malignant lymphoma in remission (disorder)|

=== |Disease (disorder)| :

|Clinical course (attribute)| = |In remission (qualifier value)|,

|Associated morphology (attribute)| = |Malignant lymphoma - category (morphologic abnormality)|

1. 4926007 |Schizophrenia in remission (disorder)|

            === |Schizophrenia (disorder)| :

|Clinical course (attribute)| = |In remission (qualifier value)|

Note: As expected, some concepts will require analysis beyond simply adding |Clinical course (attribute)|. For example, 4926007 |Schizophrenia in remission (disorder)| currently has a questionable stated parent of 191527001 |Simple schizophrenia (disorder)| (which by definition excludes some of the subtypes of |Schizophrenia in remission (disorder)|).

A small subset of "<disease> in remission" concepts may require two |Clinical course| attributes. As discussed earlier, this is not anticipated to have significant untoward effects and, where appropriate the content can be sufficiently defined even with two ungrouped |Clinical course| attributes.
Example:

As modeled, |Recurrent major depression in remission (disorder)| would also classify as a subtype of the existing concept |Recurrent major depression (disorder)|.
Some content will not be able to be sufficiently defined no matter how granular the value set. For example, the model will not be able to support conjunction of multiple disorders in varying states of remission.
Example:

|Recurrent major depression in remission (disorder)| could be modeled:

=== |Major depressive disorder (disorder)| :

           |Clinical course (attribute)| = |Recurrent (qualifier value)|,

           |Clinical course (attribute)| = |In remission (qualifier value)|

As modeled, |Recurrent major depression in remission (disorder)| would also classify as a subtype of the existing concept |Recurrent major depression (disorder)|.

Some content will not be able to be sufficiently defined no matter how granular the value set. For example, the model will not be able to support conjunction of multiple disorders in varying states of remission.

Example:

|Panic disorder with agoraphobia, agoraphobic avoidance in full remission AND panic attacks in partial remission (disorder)|

1.1.1.1..1       Model |Clinical course (attribute)| independent of any role groups

Reasons for not including |Clinical course (attribute)| in a role group with other attributes include:

1. |Clinical course (attribute)| qualifies the disease course not the |Finding site| or the |Associated morphology|.
2. Historically, |Clinical course (attribute)| has not been included in role groups and, unless the entire |Clinical finding| hierarchy is modeled with the same role grouping pattern, role grouping |Clinical course| for “<disease> in remission” concepts will result in aberrancies in classification (errors in omission). Changing the role grouping pattern for |Clinical course (attribute)| for all concepts in the |Disease| hierarchy, particularly when additional changes to the model are anticipated in the future, could be an inefficient use of resources.

Example of role grouping pattern for |Clinical course| for "<disease> in remission" concepts:

425749006 |Subacute myeloid leukemia in remission (disorder)|

===  |Subacute myeloid leukemia (disorder)|:

             |Clinical course (attribute)| = |In remission (qualifier value)|,

          { |Finding site (attribute)| =  |Bone marrow structure (body structure)|,

              |Associated morphology (attribute)| = 128934006 |Myeloid leukemia - category (morphologic abnormality)| }

Address subtypes of |General finding of observation of patient (finding)|

|General finding of observation of patient (finding)| has subtypes which also represent general patient and disease statuses/phases. These are problematic because there should be one model to represent disease status/behavior. Perpetuating different models to specify that a patient is in remission will not promote interoperability. It is possible that some implementations might use disease concepts that are precoordinated with disease status (e.g., in remission) information while others implementations might represent disease statuses such as “in remission” by combining a |Disease| concept with one of the |Clinical finding| concepts below that represents the general status of the patient or disease.

Examples of |Clinical finding| concepts that represent general patient/disease status are in bold font:

Clinical finding (finding)

Clinical history and observation findings (finding)

      General finding of observation of patient (finding)

                      Patient status finding (finding)

                            Disease condition finding (finding) 

Disease condition determination, arrested (finding) 

Disease condition determination, cured (finding) 

Disease condition determination, fairly well controlled (finding) 

Disease condition determination, moderately controlled (finding) 

Disease condition determination, slightly controlled (finding) 

Disease condition determination, uncontrolled (finding) 

Disease condition determination, well controlled (finding)

            Patient condition finding (finding) 

Patient's condition improved (finding) 

Patient in remission (finding)

Patient in early remission (finding) 

Patient in full remission (finding) 

Patient in partial remission (finding)

1.1.1.1..1       Retire 313386006 |Patient in remission (finding)| and its subtypes

At a minimum, retire the four concepts below because patients are not in remission, their diseases are in remission. (Additionally, per editorial policy, when “patient” is asserted in an FSN the concept should actually be a |Situation with explicit context|.)  Retire as |Ambiguous concept|:

• |Patient in remission (finding)| MAY BE A |Disorder in remission (disorder)|
• |Patient in early remission (finding)| MAY BE A |Disorder in remission (disorder)|

Note: There are no “<disease> in early remission” concepts in SNOMED CT as of the July 2015 release. For this reason, it is not suggested to add a new Disorder in early remission (disorder) grouper or to add a new concept “In early remission (qualifier value)” as a subtype of In remission (qualifier value).

• |Patient in full remission (finding)|  MAY BE A |Disorder in complete remission (disorder)|
• |Patient in partial remission (finding)| MAY BE A |Disorder in partial remission (disorder)|

Retire duplicate "<disease> in remission" concepts

Retire the first concept in each set below as a duplicate for the second.

• 191615005 |Recurrent major depressive episodes, in full remission (disorder)|
• 46244001 |Recurrent major depression in complete remission (disorder)| (CTV3 ID XUEZR)

• 191606003 |Single major depressive episode, in full remission (disorder)|
• 19527009 |Major depression, single episode, in complete remission (disorder)| (CTV3 ID XU8zV)

• Hebephrenic schizophrenia in remission (disorder) (CTV3 ID E1015)
• Disorganized schizophrenia in remission (disorder) (CTV3 ID XUBZ5)

• 93450001 |Erythroleukemia in remission (disorder)| (CTV3 ID XUNzX)
• 426642002 |Erythroleukemia, FAB M6 in remission (disorder)| (CTV3 ID XUfep)

Retire 255319006 |Remitting (qualifier value)|

• To prevent confusion, consider retiring 255319006 |Remitting (qualifier value)| which is only used for the three concept definitions below, only one of which is sufficiently defined.

  • |On examination - fever - remittent (finding)| (make this concept Primitive)
  • |Remittent fever (finding)| (already primitive)
  • |Slightly remittent fever (finding)| (already primitive)

   

  Although two other existing SNOMED CT concepts might potentially use |Remitting (qualifier value)| in their concept definitions, they are not currently modeled with |Clinical Course| and it is not critical that either concept be sufficiently defined because both are currently leaf concepts.

  • Relapsing remitting multiple sclerosis (disorder)
  • Remitting seronegative symmetrical synovitis with pitting edema (disorder)

Address the limited number of existing "Inactive <disease>" type concepts

Research the existing Inactive <disease> concepts listed below to determine whether they also might warrant a "<disease> in remission" description and |Clinical course| = |In remission|.

• Inactive tuberculosis (disorder)
• Inactive tuberculosis of lung (disorder)
• Inactive Ménière's disease (disorder)
• Inactive toxoplasmosis chorioretinitis (disorder)
• Chronic inactive rheumatic heart disease (disorder)
• Inactive central serous chorioretinopathy (disorder) (probably)
• Inactive central serous retinopathy with focal retinal pigment epithelial detachment (disorder)
• Proliferative diabetic retinopathy - quiescent (disorder) (synonym: Inactive proliferative diabetic retinopathy)

Establish inclusion criteria for precoordination of "<disease> in remission"

The degree to which "<disease> in remission" content should be precoordinated is a decision that is within the jurisdiction of the IHTSDO. However, the potential for combinatorial explosion for "<disease> in remission" concepts clearly exists. The new value set suggested for the |In remission (qualifier value)| subhierarchy will not be granular enough to allow all permutations of "<disease in remission" content to be sufficiently defined. In the event that a more granular level of precoordination is requested/required, expanding the |In remission (qualifier value)| value set to include more granular values (e.g., In early partial remission (qualifier value), In sustained partial remission (qualifier value) etc.) will be fairly straight forward. If necessary, an expanded value set would provide the components for postcoordination to accommodate users who need to postcoordinate more granular content. However, inclusion criteria could still be established that would limit precoordination of "<disease> in remission" content in SNOMED CT to a particular subset of concepts in the |In remission (qualifier value)| value set (e.g., first or second level subtypes).

Additional suggested guidance related to precoordination of "<disease> in remission" content includes:

Do not add “History of” “<disease> in remission (situation)” concepts.

1. 1.  “<disease> in remission” content should remain in the |Disease| hierarchy.

Examples:

• |History of tobacco use in remission less than 12 months (situation)| - actually means Tobacco use in remission less than 12 months (disorder)

• |History of rheumatoid arthritis in remission (situation)| (SIRS request ID 174142) would be added as Rheumatoid arthritis in remission (disorder)

Do not precoordinate “<disease> in remission for <time period>”.

Generally the time period should be handled by the information model. Per the SNOMED CT Editorial Guide July 2015 Section 3.4.4.3 on Numeric ranges:

 Categories that depend on numeric ranges are almost always inappropriate for precoordination.

Example:

|History of tobacco use in remission less than 12 months (situation)|

 Do not add “In remission” to normal life processes (e.g., SIRS request for |Age related cognitive decline in remission (disorder)|)

Update the Editorial Guidance Section for |Clinical course|

The Editorial Guide should be updated to reflect the final, approved concept model and inclusion criteria.

Significant design or implementation decisions / compromises

A concept model for "<disease> in remission" has been awaiting resolution for near 10 years. The long term model for "<disease> in remission" content will ultimately depend on the outcomes of other content projects which are also focused on developing a model for similar disease behavior content. In the meantime, the current proposal offers a relatively straight forward interim solution which could be implemented immediately.

Evaluation of design

Exceptions and problems

This content has dependencies on other content projects as outlined in Section 3.5.

Design Strengths

• The model can be implemented without awaiting approval for new attributes.
• The "In remission" value set can generally be ranked hierarchically and can be expanded if needed.
• The suggested concept model is consistent with URU criteria and provides a reference for terminology authors and users for pre and postcoordination of "<disease> in remission" content.
• Inclusion/exclusion criteria can be established by the IHTSDO in a fairly straightforward manner by restricting precoordination to any defined subset of the "In remission" value set.

Design Weakness

• The model further overloads the |Clinical course| attribute which already accommodates disease course and onset and will now accommodate disease phase as well. However, because the final model for disease behaviors will require an overarching vision/model, this has advantages over the addition a new approved attribute |Disease phase| which has an additional risk of contributing to modeling inconsistencies at this time (see Section 3).
• If an overarching model for disease behaviors is developed and implemented in the future, this content will require remodeling. However, implementing a consistent modeling approach in the interim should meet modeler and user needs. It will also allow development/feedback for a model that has components (e.g. the "In remission" value set) that should be transferable to a new model if one is developed.

Design Risks

Iteration One

This iteration was developed based on feedback received on the initial design provided in Section 6.1 of this document.

Outline of revised design

Initial feedback by the project reviewer indicated:

• Agreement with the concern that representing "In remission" using |Clinical course| would further overload the |Clinical course| attribute and its value set (range) by including remission status along with other seeming unrelated temporal descriptors such as "acute" and "chronic"

• Two other approaches were suggested:
  • Create a new attribute such as |Disease activity| and include as its value set (range) qualifier values that specifically represent disease activities (e.g., remission, recurrent, relapsing, active, relapsing/remitting, etc.) which might better meet URU criteria.

• • Model |<Disorder X> in remission| as a stated child of |Disorder X| and of |Disorder in remission|.

Considering the initial options as well the two options suggested in the feedback phase, the goal remains to outline an option that reasonably addresses the objective of defining "in remission" content within the scope of a single project while mitigating risk.

Whether |Disease course|, |Disease phase| or |Disease activity| is used to define "in remission" concepts, there are interim concessions/risks related to addressing "in remission" without addressing the path forward for other similar disease modifiers (e.g., course, severity, episodicity, stage, phase etc.) and their values sets.

The risks associated with |Clinical course| were already addressed in this document as were the risks related to |Disease phase|. However, the drawbacks associated with |Disease phase| overlap with the drawbacks associated with the proposal use a new |Disease activity| attribute. They are summarized here as a prelude to addressing the proposed option of using |Disease activity| to model "in remission" concepts.

1. The previously considered |Disease phase (attribute)| option

Initial considerations against |Disease phase| included:

1. 1. |Disease phase| is not currently an approved attribute.
   2. Making it an approved attribute raises a number of potential issues which are not necessarily straight forward to address, would require further testing, and are outside of the scope of the "in remission" project.

They include:

The probable range for |Disease phase| would be 303105007 |Disease phases (qualifier value)|). These values would also need to be addressed before they are allowed as values for |Disease phase|. The current values include:

• |Disease phases (qualifier value)|
  • Accelerated phase (qualifier value)
  • Acute phase (qualifier value)
  • Chronic phase (qualifier value)
  • Convalescent phase (qualifier value)
  • Prodromal phase (qualifier value)
  • Relapse phase (qualifier value)
  • Remission phase (qualifier value)
  • In complete remission (qualifier value)
  • In partial remission (qualifier value)
  • Transformed phase (qualifier value)
    
    

The overlap with between the value sets for the |Clinical course| and |Disease phase| attributes would need to be addressed before |Disease phase| was approved as an attribute. Otherwise, there would be two ways of modeling some acute or chronic phases of disease.

|Clinical course| is "currently used to represent both the course and onset of a disease" and some of the values (e.g., onset values) currently overloading the |Clinical course| attribute will appear even less acceptable if the more appropriate |Disease phase| attribute is available to capture this aspect of a concept's definition.
If the issue of the overlapping value sets is resolved, disentangling and remodeling the concepts which are currently modeled with the conflated values (e.g., |Sudden onset AND short duration (qualifier value)| or its subtypes) may be a significant task. For example, in the stated view, |Sudden onset AND short duration (qualifier value)| is referenced in 473 concept definitions as a value for |Clinical course|.

1. 1. The newly proposed |Disease activity (attribute)| option

In considering the feedback proposal to "create a new attribute such as disease activity and include as its range, qualifier values that specifically represent disease activities such as remission, recurrent, relapsing, active, relapsing/remitting", initial considerations against |Disease activity| and its URU include:

1. 1. 1. |Disease activity| is not currently an approved attribute.
      2. Making it an approved attribute opens additional issues to address which are not necessarily straight forward, require further testing, and are outside of the scope of the "in remission" project. They include:

1. 1. 1. 1. What other values should be in the range for |Disease activity|?

For example, "relapse" is the disease "activity" that often follows "remission". One of the suggested values for |Disease activity| was "relapsing". A number of qualifier values in SNOMED CT, which already exist to address the notion of "relapse/relapsing", highlight the confusion as to how these disease descriptors should be represented (e.g., as phases, stages, episodes, courses, activities etc.):

• • • • Relapse phase (qualifier value)
      • Relapse stage (qualifier value)
      • Relapse episode (qualifier value)
      • Relapsing course (qualifier value)

1. 1. 1. A review of some existing unapproved attributes (below), illustrates their overlap with each other as well as with the newly suggested |Disease activity| attribute and with other approved attributes (e.g., |Clinical course (attribute)|, |Episodicity (attribute)| and |Severity (attribute)|). This again highlights the variety of options and the potential confusion in deciding on a correct attribute to represent some of these disease descriptors:

• • • • Condition activity (attribute)
      • Condition course (attribute)
      • Condition severity (attribute)
      • Course of illness (attribute)
      • Pattern of disease (attribute)
      • Pattern of episode (attribute)
      • Period of onset (attribute)
      • Progression (attribute)
      • Clinical status (attribute)
      • Disease phase (attribute)

1. 1. 1. Is |Disease activity| is a better choice than |Disease course| for modeling "in remission"?
         1. The Ontology for General Medical Science (OGMS) definitions (pg. 16 of the document) actually define remission as "part of a disease course":
            
            
         • Disease course - The totality of the processes through which a given disease instance is realized. 
         • Remission - A part of a disease course that includes a temporary convalescence. 
         • Relapse - A part of a disease course that occurs after an incomplete remission and that is similar to earlier parts of the disease course. 

1. 1. 1. 1. DSM-V includes "in remission" qualifiers under "Course Specifiers."

The considerations above led to the conclusion that best approach for a model for "in remission" might be one that defers the issue of which attribute to use (and thereby the issue of having to address their value sets) while still providing an option to sufficiently define "in remission" concepts. This could be accomplished by adding a set of high-level "Disorder in <remission>" grouper concepts and assigning them as stated parents for "in remission" concepts.
Introducing a set of high-level "Disorder in <remission>" grouper concepts, which essentially correspond to the "In remission (qualifier value)" value set initially proposed in this document, would meet the immediate requirement to define the majority of "in remission" concepts. If an overarching model for disease courses, stages, phases and/or activities and their value sets is proposed in the future, it should be fairly straight forward to sufficiently define the "Disorder in <remission>" grouper concepts and their subtypes using a designated attribute that allows the "In remission (qualifier value)" value set previously proposed in Section 6.1.

Revised modeling recommendations

Add new Disorder in remission (disorder) grouper concepts

Add a set of high-level grouper concepts to adequately represent the set of "In remission" qualifier values initially proposed in Section 6.1.1.2 - Modeling Recommendations.
The high-level taxonomy would require the addition of 5 new high-level primitive grouper concepts and 4 new sufficiently defined grouper concepts.

Proposed new grouper concepts: 

*SD indicates that the concept should be sufficiently defined on the basis of 2 stated primitive parents.
The concepts above with "complete" in their FSN should also be given a corresponding synonym with "full" replacing "complete".

• • Disorder in full remission (disorder)

Synonym: Disorder in complete remission

• • Disorder in spontaneous full remission (disorder)

Synonym: Disorder in spontaneous complete remission

• • Disorder in full remission in response to treatment (disorder)

Synonym: Disorder in complete remission in response to treatment


Example - The proposed high-level taxonomy*

*Added in a test environment

Example: Disorder in spontaneous full remission (disorder) – A sufficiently defined grouper*

*Added in a test environment

Model existing "<disease> in remission" concepts

The list of "<disease> in remission" concepts as of the July 2015 Release is provided in Appendix B.

Add an appropriate "Disorder in <remission>" grouper parent to each of the more granular "<disease> in remission" concepts

For existing "<disease> in remission" concepts, add an appropriate "Disorder in <remission>" grouper concept as a stated parent. Many of the concepts will be able to be sufficiently defined.


Examples - Expressions of stated concept definitions
Concepts in italics represent the grouper concepts which have yet to be added to SNOMED CT. The concepts in the examples below could all be sufficiently defined.

1. 1. Mood disorder in partial remission (disorder)

=== |Mood disorder (disorder)| +
|Disorder in partial remission (disorder)|
Thus, the definition for |Mood disorder in partial remission (disorder)| would change from:

to:

1. 1. Major depression, single episode, in complete remission (disorder)

=== |Major depression, single episode (disorder)| +
|Disorder in full remission (disorder)|

1. 1. Malignant lymphoma in remission (disorder)

=== |Disorder in remission (disorder)| :

Note: The definition above is in accordance with current policy of assigning only primitive parents.

1. 1. Schizophrenia in remission (disorder)

=== |Schizophrenia (disorder)| +
|Disorder in remission (disorder)|
Note: As expected, some "in remission" concepts will require analysis beyond simply adding the appropriate new "Disorder in <remission>" grouper as a stated parent. For example, 4926007 |Schizophrenia in remission (disorder)| currently has a questionable stated parent of 191527001 |Simple schizophrenia (disorder)| (which by definition excludes some of the current subtypes of |Schizophrenia in remission (disorder)|). |Simple schizophrenia (disorder)| should be removed as a stated parent.

Approach for "<disease> in remission" concepts with multiple disorders in varying states of remission

The proposed model will not be able to support conjunction of multiple disorders in varying states of remission (e.g., 22230001 |Panic disorder with agoraphobia, agoraphobic avoidance in full remission AND panic attacks in partial remission (disorder)|) because in there is not a way to "bind" a specific "Disorder in <remission>" grouper (e.g., |Disorder in full remission (disorder)|) to the specific disorder it modifies (e.g., |Agoraphobic avoidance (disorder)|).
The test below using a hypothetical example (even simpler than that of the existing concept |Panic disorder with agoraphobia, agoraphobic avoidance in full remission AND panic attacks in partial remission (disorder)|) illustrates why concepts with multiple disorders in varying states of remission cannot be sufficiently defined using the proposed model.
Example: |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| (hypothetical test concept)
To model |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| the following concepts were added in a test environment:

1. 1. Panic attacks in partial remission (disorder)

=== |Panic attack (finding)| +
|Disorder in partial remission (disorder)|

Note: |Panic attack (finding)| was used for the purpose of this exercise, because it already existed in SNOMED CT. Had it also existed, |Panic attacks (disorder)| might have been more appropriate because |Panic attack (finding)| might actually represent a single event rather than the disorder.)

1. 1. Agoraphobia in full remission (disorder)

=== | Agoraphobia (disorder)| +
|Disorder in full remission (disorder)|

1. 1. Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)

=== |Agoraphobia in full remission (disorder)| +
|Panic attacks in partial remission (disorder)|

Problems will arise with classification if the following two concepts are also added:

1. 1. Panic attacks in full remission (disorder)

=== |Panic attack (finding)|+
|Disorder in full remission (disorder)|

1. 1. Agoraphobia in partial remission (disorder)

=== | Agoraphobia (disorder)| +
|Disorder in partial remission (disorder)|

Recall the stated sufficient definition of |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)|:
=== |Agoraphobia in full remission (disorder)| +

However upon classifying, |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| also classifies as a subtype of |Agoraphobia in partial remission (disorder)| and |Panic attacks in full remission (disorder)| which are both incorrect supertypes.

Therefore, to prevent this incorrect classification, the subset of concepts with conjunction of multiple disorders in varying states of remission should simply be stated subtypes of the most general |Disorder in remission (disorder)| grouper. If a future solution is proposed that offers attributes to address an overarching solution for the many related concepts representing various disease phases, courses and stages, those attributes can be used to define the high level "Disorder in <remission>" groupers proposed here and role grouping can then facilitate correct subsumption for concepts with dual "in remission" statuses.

Address subtypes of |General finding of observation of patient (finding)|

• • Patient in early remission (finding)

    MAY BE A

    Disorder in remission (disorder)

Note: As of the January 2015 release, there are no "<disease> in early remission" concepts in SNOMED CT. For this reason, it is not suggested to add a new |Disorder in early remission (disorder)| grouper at this time.

• • Patient in full remission (finding)

    MAY BE A

    Disorder in full remission (disorder)

  • Patient in partial remission (finding)

    MAY BE A

    Disorder in partial remission (disorder)

Consider edits to the subtypes of |Disease condition finding (finding)|

Although the subtypes of |Disease condition finding (finding)| are considered to be out of scope for this project, they should also be reviewed as a separate project.

Retire duplicate "<disease> in remission" concepts

Retire the first concept in each set below as a duplicate for the second.

• • 191615005 |Recurrent major depressive episodes, in full remission (disorder)|
  • 46244001 |Recurrent major depression in complete remission (disorder)| (CTV3 ID XUEZR)

• • 191606003 |Single major depressive episode, in full remission (disorder)|
  • 19527009 |Major depression, single episode, in complete remission (disorder)| (CTV3 ID XU8zV)

• • Hebephrenic schizophrenia in remission (disorder) (CTV3 ID E1015)
  • Disorganized schizophrenia in remission (disorder) (CTV3 ID XUBZ5)

• • 93450001 |Erythroleukemia in remission (disorder)| (CTV3 ID XUNzX)
  • 426642002 |Erythroleukemia, FAB M6 in remission (disorder)| (CTV3 ID XUfep)

Address the limited number of existing "Inactive <disease>" type concepts

Research the existing "Inactive <disease>" concepts listed below to assess whether they might also warrant a "<disease> in remission" description and a stated parent of a "Disorder in <remission>" grouper.

• • Inactive tuberculosis (disorder)
  • Inactive tuberculosis of lung (disorder)
  • Inactive Ménière's disease (disorder)
  • Inactive toxoplasmosis chorioretinitis (disorder)
  • Chronic inactive rheumatic heart disease (disorder)
  • Inactive central serous chorioretinopathy (disorder) (probably)
  • Inactive central serous retinopathy with focal retinal pigment epithelial detachment (disorder)
  • Proliferative diabetic retinopathy - quiescent (disorder) (synonym: Inactive proliferative diabetic retinopathy)

Establish inclusion criteria for precoordination of "<disease> in remission"

The degree to which "<disease> in remission" content should be precoordinated is a decision that is within the jurisdiction of the IHTSDO. However, the potential for combinatorial explosion for "<disease> in remission" concepts clearly exists. Regardless of whether the model for "disease in remission" uses an approach of representing "in remission" through a stated "Disorder in <remission>" parent or by using an attribute value pair, the level of granularity of some "<disease> in remission" concepts suggests that all permutations of "<disease> in <remission>" content will not be able to be sufficiently defined.
However, if more granular levels of precoordination are requested/required, the set of high-level "Disorder in <remission>" grouper concepts can be expanded (e.g., by adding Disorder in early remission (qualifier value), Disorder in sustained remission (qualifier value), Disorder in early partial remission (qualifier value) etc.). If necessary, this would provide the components for postcoordination to accommodate users with a need to postcoordinate more granular content. However, inclusion criteria could still be established that would limit precoordination of "<disease> in remission" content in SNOMED CT to a particular level of the "Disorder in <remission>" groupers.

Additional suggested guidance related to precoordination of "<disease> in remission" content includes:

1. 1. Do not add "History of" "<disease> in remission (situation)" concepts.

"<disease> in remission" content should remain in the |Disease| hierarchy.
Examples:

• • History of tobacco use in remission less than 12 months (situation)

    actually means Tobacco use in remission less than 12 months (disorder)

• • History of rheumatoid arthritis in remission (situation)

    (SIRS request ID 174142) should be added as Rheumatoid arthritis in remission (disorder)

1. 1. Do not precoordinate "<disease> in remission for <time period>".

Generally, the time period should be handled by the information model. Per the SNOMED CT Editorial Guide July 2015 Section 3.4.4.3 on Numeric ranges:
Categories that depend on numeric ranges are almost always inappropriate for precoordination.
Example:

Update the Editorial Guidance Section for |Disease in remission| Concepts

The Editorial Guide should be updated to reflect the final, approved concept model and inclusion criteria.

Significant design or implementation decisions / compromises

A concept model for "<disease> in remission" has been awaiting resolution for near 10 years. The long term model for "<disease> in remission" content will ultimately depend on the outcomes of other content projects which are also focused on developing a model for similar disease behavior content. In the meantime, the current proposal offers a relatively straight forward interim solution that can be adapted should future models propose new attributes to represent disease behaviours.

Evaluation of revised design

Exceptions and Problems

This content has some dependencies on other content projects as outlined in Section 3.5.

Design Strengths

• • The model can be implemented without awaiting approval for new attributes.
  • The proposed high-level "Disorder in <remission>" grouper concepts are straightforward to rank hierarchically and can be extended if needed.
  • The suggested concept model is consistent with URU criteria and provides a reference for terminology authors and users for pre and postcoordination of "<disease> in remission" content.
  • Inclusion/exclusion criteria can be established by the IHTSDO in a fairly straightforward manner by restricting precoordination to any defined subset of the proposed set of high-level "Disorder in <remission>" grouper concepts.

Design Weakness

• • The model relies on the stated assertion of a high-level grouper parent in order to define most "<disease> in remission" content. However, this represents essentially the same level of editor effort as would be required to assign an attribute value pair to these concepts in the stated view.

Design Risks

Recommendation

Detailed design final specification

The detailed design recommendations are included in Section 6.2.1- Outline of revised design. The plan does not require approval of a new attribute and adds a limited number of high-level "Disorder in <remission>" grouper concepts. The content requiring editing is limited and should not significantly impact other areas of content.

Iteration plan

As outlined in Section 6.2.1 Outline of revised design.

Quality program criteria

Quality metrics

Quality metric 1

Quality metric 2

Project Resource Estimates

Based on existing content in the July 2015 International Release and SIRS requests as of July 2015, the estimated number of concepts requiring editing is between 300 and 400 concepts.

Adding the new "Disorder in <remission>" groupers is a straightforward modeling task.
Many of the "<disease X> in remission" concepts will not have other attributes and can be sufficiently defined on the basis of a "stated <Disease X>" parent and a stated "Disorder in <remission>" grouper parent. Overall, many of the "<disease> in remission" concepts are low-level concepts that generally will have no, or only a few, other "<disease> in remission" concepts as subtypes. A review of the existing "<disease> in remission" concepts indicates that about 50% appear to be relatively straight forward while roughly 50% will likely involve some review/tangential modeling.
There are some tangential issues that should be addressed for a number of these concepts (See Appendix C). Therefore, at an estimated rate of about 4-6 concepts/day (with between 300-400 concepts to edit), the project is estimated to take roughly 10 weeks of an FTE. The estimate could be lower if a compromise is made to only attempt to sufficiently define the roughly 50% of the content that is more straightforward to model. The remainder could be left primitive, but an appropriate stated "Disorder in <remission>" grouper parent could still be added so that the concepts will be retrieved as subtypes of Disease in remission (disorder) even though they will not subsume subtypes or be detected in equivalency testing. Leaving this content primitive is generally a low risk from the standpoint of equivalency testing because of fairly consistent naming patterns for <disease> in remission content.
The risks and benefits of addressing this content have already been outlined in Sections 4 and 6.

Projection of remaining overall project resource requirements

Expected project resource requirement category

The project should not require project management and the estimated resource requirement is small.

Expected project impact and benefit

The impact to existing content should be low on the basis that:

• • Many of the existing concepts to be edited are low-level or leaf concepts
  • New concept requests appear to be for fairly low-level or leaf concepts
  • No major hierarchical change is suggested
  • The proposal works within the existing concept model

The benefit is a model to pre and postcoordinate "<disease> in remission" content and to sufficiently define a significant proportion of content that was previously primitive. An additional benefit is that the set of high-level "Disorder in <remission>" groupers concepts could be used to assist in defining inclusion and exclusion criteria for "<disease> in remission" content.

Indicative resource estimates for construction, transition and maintenance:

Construction and transition phase: ~300-400 concepts to be authored (~220-300 existing and ~80 in SIRS)
Maintenance phase: Based on existing requests, < 80 new concept requests/yr.

Appendix A - "<disease> in remission" concepts in the NLM CORE Problem List Subset

Of the 34 "<disease> in remission" concepts in the NLM Core Subset of SNOMED CT^® , 4 are related to malignant disease and 30 are in the mental health and substance abuse/dependency category. (The two concepts in bold are potential duplicates.)
191889006 |Tobacco dependence in remission (disorder)|
191839003 |Cannabis dependence in remission (disorder)|
191821007 |Opioid dependence in remission (disorder)|
191833002 |Cocaine dependence in remission (disorder)|
191845006 |Amphetamine or psychostimulant dependence in remission (disorder)|
191875001 |Combined drug dependence, excluding opioid, in remission (disorder)|
191813001 |Chronic alcoholism in remission (disorder)|
191884001 |Nondependent alcohol abuse in remission (disorder)|
191914006 |Nondependent opioid abuse in remission (disorder)|
191895007 |Nondependent cannabis abuse in remission (disorder)|
191938005 |Nondependent mixed drug abuse in remission (disorder)|
191920007 |Nondependent cocaine abuse in remission (disorder)|
42810003 |Major depression in remission (disorder)|
70747007 |Major depression single episode, in partial remission (disorder)|
19527009 |Major depression, single episode, in complete remission (disorder)|
191606003 |Single major depressive episode, in full remission (disorder)|
68019004 |Recurrent major depression in remission (disorder)|
46244001 |Recurrent major depression in complete remission (disorder)|
33135002 |Recurrent major depression in partial remission (disorder)|
91856007 |Acute lymphoid leukemia in remission (disorder)|
91860005 |Acute myeloid leukemia in remission (disorder)|
94704006 |Multiple myeloma in remission (disorder)|
92813000 |Chronic lymphoid leukemia in remission (disorder)|
85248005 |Bipolar disorder in remission (disorder)|
35481005 |Mixed bipolar I disorder in remission (disorder)|
36583000 |Mixed bipolar I disorder in partial remission (disorder)|
111485001 |Mixed bipolar I disorder in full remission (disorder)|
78269000 |Bipolar I disorder, single manic episode, in partial remission (disorder)|
63249007 |Manic bipolar I disorder in partial remission (disorder)|
30935000 |Manic bipolar I disorder in full remission (disorder)|
49512000 |Depressed bipolar I disorder in partial remission (disorder)|
22121000 |Depressed bipolar I disorder in full remission (disorder)|
191574005 |Schizoaffective schizophrenia in remission (disorder)|
63181006 |Paranoid schizophrenia in remission (disorder)|

Appendix B – "<disease> in remission" concepts in SNOMED CT

"<disease> in remission" concepts in the July 2015 International Release.

Appendix C - Modeling inconsistencies to be addressed as part of the <disease> in remission project

Properly adding or editing "<disease> in remission" concepts relies to a certain degree on the state of the current content with which it will be integrated. The two examples provided are indicators of how current modeling or policy may have an impact on the concept definitions for "<disease> in remission" concepts as well as on the estimated editing time for this project.

Primitive "<Mental disorder> in remission" Concepts

The majority of "<disease> in remission" concepts are in the area of mental health and the concepts in this area of mental health are often primitive and undermodeled. In order to be purposeful, ideally the editing of "<mental disorder> in remission" concepts should involve finding appropriate parents. However for many of the "<mental disorder> in remission" concepts, there may be additional appropriate primitive parents beyond those proposed in Section 6.2 to sufficiently define the concepts.
For example, the hypothetical concept |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| (proposed in section 6.2.2.2..2) would also be an appropriate subtype of the existing concept |Agoraphobia with panic attacks (disorder)|. However, it will not classify as a subtype of |Agoraphobia with panic attacks (disorder)| because |Agoraphobia with panic attacks (disorder)| is primitive and therefore would need to be added as a stated parent of |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)|.
However, |Agoraphobia with panic attacks (disorder)| can probably be sufficiently defined. Currently, |Agoraphobia with panic attacks (disorder)| is a subtype of | Agoraphobia (disorder)| but not a subtype of |Panic attack (finding)|. If it had a second, appropriate stated parent it might be able to be sufficiently defined.
191722009 | Agoraphobia with panic attacks (disorder)|


However, it is possible that |Panic attack (finding)| was not chosen as a second stated parent for |Agoraphobia with panic attacks (disorder)| because |Panic attack (finding)| may be considered have a different meaning than "Panic attacks (disorder)" (which does not currently exist) which might better capture the idea of recurrent panic attacks. This is somewhat analogous to SNOMED CT having the concept |Seizure finding)| to represent a single seizure and |Epilepsy (disorder)| to represent the disorder involving recurrent seizures. Nonetheless, these are the types of time consuming issues that an editor must consider in order for a new concept such as |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| to have appropriate supertypes.
Another parent that might subsume the hypothetical concept |Agoraphobia in full remission co-occurrent with panic attacks in partial remission (disorder)| would be 35607004 |Panic disorder with agoraphobia (disorder)| However, 35607004 |Panic disorder with agoraphobia (disorder)| is also currently primitive although it could be sufficiently defined with its current stated parents.
35607004 |Panic disorder with agoraphobia (disorder)|

These basic examples of the current state of the "mental health" concepts (into which the "<mental disorder> in remission" concepts would be integrated) led to an increase in the estimated editing time for this project.

Modeling to the nearest proximal primitive parent

Current editorial policy guidance is to model to the nearest proximal primitive parent where possible. Unless current inconsistencies in the modeling of the concepts (outside of the modeling of "in remission" status) are addressed, modeling to the nearest proximal primitive may result in some "<disease> in remission" concepts losing their stated, sufficiently defined "<disease> in remission" parents. The risk to user implementations of the loss of a correct parent may be more significant than the benefit of adding the "In remission" characteristic to the concept definitions. Correcting the tangential inconsistencies in the modeling of the concepts while editing the "<disease> in remission" concepts can mitigate this risk.
Example:
427374007 |Immunoproliferative neoplasm in remission (disorder)| is currently modeled as a stated child of the sufficiently defined concept |Immunoproliferative neoplasm (disorder)| which has the following stated view:

However, |Immunoproliferative neoplasm (disorder)| has an aberrancy in the inferred view:

Normally, if the value for |Associated morphology| of the stated parent is a supertype of the value for |Associated morphology| in the child, the classifier will remove the more general value and only the more granular value for |Associated morphology| will remain the inferred view. However, as can be seen above, the inferred view of |Immunoproliferative neoplasm (disorder)| has its stated value for |Associated morphology| as well as the value for |Associated morphology| inherited from |Neoplastic disease (disorder)| (its stated parent). This results in an incorrect concept definition for |Immunoproliferative neoplasm (disorder)| and, even though it is sufficiently defined, it may not inherit all of its appropriate subtypes.
This aberrancy of two |Associated morphology| attributes indicates that either:

1. 1. 414467006 |Immunoproliferative neoplasm (morphologic abnormality)| should be made a subtype of 108369006 |Neoplasm (morphologic abnormality)| in the |Morphologically abnormal structure (morphologic abnormality)| subhierarchy

OR

1. 1. Immunoproliferative neoplasm (disorder)

      should not be a subtype of

      Neoplastic disease (disorder)

Under the current guidance of modeling to the proximal primitive parent, |Immunoproliferative neoplasm in remission (disorder)| would no longer be modeled as a stated child of |Immunoproliferative neoplasm (disorder)|. Instead it would be modeled:

If the error in the modeling of |Immunoproliferative neoplasm (disorder)| is not corrected, |Immunoproliferative neoplasm in remission (disorder)| will not be inferred as a subtype of |Immunoproliferative neoplasm (disorder)| because it is missing |Associated morphology (attribute)| = 108369006 |Neoplasm (morphologic abnormality)| which is part of the current, erroneous definition of |Immunoproliferative neoplasm (disorder)|. The risk to user implementations of the loss of this parent for |Immunoproliferative neoplasm in remission (disorder)| may be more significant than the benefit of sufficiently defining |Immunoproliferative neoplasm in remission (disorder)|.
While the |Associated morphology| attribute is not part of the in remission project, this is an example of the type of collateral editing that results in an estimate of only 4-6 concepts being edited/day. In this case, the error in the definition of |Immunoproliferative neoplasm (disorder)| must also be corrected (and its descendants must then also be reviewed to ensure they are also consistently modeled and that no descendants are lost).

Appendix D - <disease> status notes

Taken from a document called Event-condition-episode_notes-ks.doc
Rough notes for event/condition/episode project group
Kent Spackman
2008-04-12.
Models for disease status, remission, severity, episodicity, phase, stage, control:
Many codes in SNOMED refer to the status of a disease. At present there is a "hold" on the pre-coordination of new content involving severity and remission status, and there is no agreed way to model content involving staging or degree of control of a disease.
There has been some debate about whether these are subtypes of the disease, or whether they are subtypes of a situation in which the disease is present. This short paper summarizes the latter point of view and presents some very early draft ideas moving towards a possible solution that would allow resuming the pre-coordination of codes that mention disease status.
Kinds of disease status information:
In remission, in relapse, in partial/complete remission -> disease phase (attribute)
In control, not in control, in poor control, in good control -> NEW attribute needed.
Disease phase (acute phase, convalescent phase, etc) -> disease phase (attribute)
Severity (mild, moderate, severe) -> severity (attribute)
Stage -> staging of disease (attribute)
Episodicity -> episodicity (attribute)
"finding method" and "finding informer" relate to the knowing (epistemological concerns).
Consider the way to model "disease X, in remission" as a situation:
Options include

1. 1. Situation, {associated finding = disease X, finding-context = in remission}
   2. Situation,{associated finding = patient in remission (finding), finding-context = known present},

{associated finding = disease X, finding-context = known present}

1. 1. Situation, {associated finding = disease X,

finding-context = known present,
disease-phase = in remission}
All options will make "disease X present, in remission" a subtype of "disease X present".
Problems:
Option 1 problems:
"In remission" would not be a valid value for finding-context, and it would be a bad idea to combine the present/absent/uncertain dimension with the disease phase dimension.
Option 2 problems:
Currently "in remission" is a value for "severity", while we have a separate finding called "patient in remission". This is in addition to the unused qualifier values in the disease phase hierarchy. Perpetuating three different ways to specify that a patient is in remission seems like the wrong thing to do.
Option 3 appears to be the best, and suggests that at the same time we should consider movement of "severity", "episodicity", "finding informer", and "finding method" from being finding attributes to being situation attributes, activate "staging of disease", and add a new attribute "disease control" with a value set.

Previous version: