LINKS:

JIRA:  IHTSDO-320 - Getting issue details... STATUS

Document review: 

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from the IHTSDO [or a Member of the IHTSDO] is not controlled by the IHTSDO, and may have been modified and may be out of date.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 Editorial Guidance - Background
3.4.2 Subjectivity of Procedure Prioritization
3.4.3
3.4.4 Regional and Institutional Variation in Procedure Prioritization
3.4.5 SNOMED CT International Request Submission (SIRS) Requests Related to Prioritization of Procedures
3.5 Subsidiary and interrelated problems
4 Risks / Benefits
4.1.1 Risks of not addressing the problem
4.1.2 Risks of addressing the problem
5 Requirements: criteria for success and completion
5.1 Criteria for success/completion
5.1.1 Consistent meaning, modeling and editorial policy
5.2 Strategic and/or specific operational use cases
5.2.1 Clear editorial policy development for
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 Significant design or implementation changes
6.2.3 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
8.1.3 Quality metric 3
9 Project Resource Estimates
9.1 Estimate of project size:
9.1.1 Editing
9.1.2 Providing guidance for Procedures by Priority for the Editorial guide
9.2 Scope of construction phase
9.3 Projection of remaining overall project resource requirements
9.3.1 Expected project resource requirement category
9.3.2 Expected project impact and benefit
9.3.3 Indicative resource estimates for construction, transition and maintenance:

Glossary

Domain Terms

Introduction

Purpose

The purpose of this project is:

1. To evaluate whether the attribute 260870009 |Priority (attribute)|, used to define the priority of a procedure, meets URU criteria and whether it adds value to pre-coordinated and/or post-coordinated SNOMED CT content
2. To propose a model or course of action for if/how the attribute should be used

Audience and stakeholder domain

The audience for this document includes all standards terminology leaders, implementers and users but is especially targeted at those stakeholders:

• Developing pre-coordinated SNOMED CT |Procedure by priority| content in the IHTSDO International Release
• Developing post-coordinated SNOMED CT |Procedure by priority| content)
• Implementing SNOMED CT in the Electronic Health Record, particularly in the surgical domain
• Involved in quality assurance of content in the |Procedure by priority| and |Procedure with explicit context| hierarchies
• Concerned with SNOMED CT interoperability

Input from stakeholders

Internal Stakeholders: The inability of |Priority (attribute)| to meet URU criteria has been an ongoing issue for internal SNOMED CT content modelers and was originally submitted to the IHTSDO in 2008 by the internal editing team.
External Stakeholders: In recent years, there have also been some requests in the SNOMED CT International Request Submission (SIRS) System which indicate users' needs for pre-coordinated |Procedure by priority| content and also highlight some problems related to |Priority (attribute)|.

Content Developers

For insight into some of the needs of content developers and implementers related to |Procedure by priority| content, please refer to Section 3.4.5 on SIRS Requests related to |Procedure by priority| content.

Implementers

Data on implementation of procedure prioritization in the EHR is sparse. An old and small code usage dataset obtained from a U.K vendor (using a CTV3 system that had implemented the templates file and exposed the attributes to GP end users) showed that only a few attributes (e.g., Laterality, Severity, Episodicity, and Site) were used with any regularity. In this U.K. dataset, |Priority (attribute)| was used infrequently with the most frequently assigned value for |Priority (attribute)| being |Scheduled - priority (qualifier value)|.
U.K. Vendor usage data for |Priority (attribute)|:

Degree of consensus on the statement of problem

As will be demonstrated in Section 3, there is generally agreement among internal SNOMED CT content modelers that |Priority (attribute)| does not meet URU (understandable, reproducible, useful) criteria. For this reason, the addition of new |Procedure by priority| content had been on hold in recent years pending the outcome of the "artf6250: PRIORITY" project. During this period, the following guidance was approved by the IHTSDO as a standard reply to submitters requesting new |Procedure by priority| content:
Pre-coordination of new <priority> <procedure> content is on hold and will be addressed as part of an IHTSDO project.
Achieving stakeholder consensus with respect to a proposed solution for an attribute that is part of the SNOMED CT Concept Model may be more challenging than achieving consensus that there is a problem with the attribute. Lack of data with respect to implementation of |Priority (attribute)| may also lead to uncertainty about the impact of changes and may ultimately influence the proposed solution, notwithstanding the current unsatisfactory status of the attribute.

Statement of the problem or need

Summary of problem or need, as reported

IHTSDO Content Tracker description for artf6250 - PRIORITY:
The PRIORITY attribute requires future review for reproducibility and consistency. There is some subjectivity to assigning this attribute. It is generally assigned when the Fully Specified Name (FSN) explicitly states the priority [e.g. Emergency operation (procedure)]. However, it is easily omitted when the FSN does not explicitly state the priority.

Summary of requested solution

While a specific solution was not proposed with the initial artifact, review of an attribute for reproducibility and consistency normally requires Quality Assurance processes which include:

1. Review of Editorial Guidance on use of the attribute.
2. Review of content where the attribute is applied to evaluate whether:
   1. It is used correctly in the concept definition
   2. The classification results are correct
3. Review for errors of omission - concepts where the attribute should be applied but was not
4. Review of the attribute's value set (|272125009 |Priorities (qualifier value)|) for completeness and for incorrect values

Initial proposals for a solution are provided the Solution Development Section (Sections 6).

Statement of problem as understood

The 260870009 |Priority (attribute)| attribute is intended to subclass a |Procedure (procedure)| concept according to its priority. However, the attribute has been used sparsely and inconsistently in concept definitions. As of the January 2015 International Release, |Priority (attribute)| had been used in 162 stated procedure definitions and in 191 inferred procedure definitions.
Issues related to the use of |Priority (attribute)| include:

1. Subjectivity related to interpretation of the "priority" of procedures for FSNs where priority is explicitly stated and, even more so, for FSNs where priority is not explicitly stated
2. Ambiguity in the meaning of the allowed values for |Priority (attribute)| (the range is 272125009 |Priorities (qualifier value)|)
   1. Some allowed values are ambiguous in their own right
   2. Some have a meaning that is relative to the procedure that is being qualified

Examples:

• Emergent surgical priority may have a different meaning (with respect to urgency and timeline) than emergent administrative priority
• Even within a specialty realm such as Surgery, surgical priorities can have different definitions in different settings and specialties

1. Overlap between values for |Priority (attribute)| (the range for which is 272125009 |Priorities (qualifier value)|) and for |Procedure context (attribute)| (the range for which is 288532009 |Context values for actions (qualifier value)|)

For the reasons stated, |Priority (attribute)| does not reliably differentiate or retrieve |Procedure by priority (procedure)| concepts. This is particularly problematic because |Procedure by priority (procedure)| is sufficiently defined which misleads users to assume that the concept will classify its appropriate subtypes. Although |Procedure by priority (procedure)| classifies some appropriate subtypes, many appropriate subtypes are omitted and some subtypes are inappropriate.
Nevertheless, |Priority (attribute)| may be useful for differentiating some emergent or non-emergent procedures for scheduling, billing or other purposes. Therefore, even if it is retired as a defining attribute in the International Release, the question of whether it may still have a purpose for post-coordination or in pre-coordinated content in local extensions should be considered. However, the risk/benefit ratio for the use of |Priority (attribute)| should still be taken into account for these use cases.

Detailed analysis of reported problem, including background

Editorial Guidance - Background

The SNOMED CT® Editorial Guide January 2015 (Section 6.2.2.7 PRIORITY) offers the following guidance for the |Priority| attribute:
This attribute refers to the priority assigned to a procedure.
Domain: |Procedure| hierarchy
Range: 272125009 |Priorities (qualifier value)|
Example:

• |PRIORITY| |Emergency (qualifier value)|
It is worth noting that some procedures with priority (e.g., an Emergency caesarean section) may be performed differently in an emergency than when done under more routine conditions. However, this is not necessarily the case for many of the |Procedure by priority| concepts where the technique for performing the procedure is basically the same regardless of the urgency/prioritization for the procedure. Additionally, based on the Editorial Guidance, the purpose of this attribute is not to identify procedures where the technique may vary based on priority, the purpose is to identify the priority of the procedure.

Subjectivity of Procedure Prioritization

There is a significant degree of subjectivity in assigning priority to procedures. Without clear-cut definitions and criteria for how to prioritize procedures, it is often not clear which procedures should be assigned |Priority (attribute)| and when a procedure might be deemed to be essential but not necessarily emergent.
Examples:

• Intracoronary artery thrombolytic infusion (procedure)
• Repair of rupture of coronary artery (procedure)
• Emergency excision of normal appendix (procedure)
• Control of hemorrhage (procedure)
• Thoracoscopy with control of traumatic hemorrhage (procedure)
• Repair of chest wall herniation of lung (procedure)
• Excision of ruptured appendix by open approach (procedure)
• Stabilization of spinal dislocation (procedure)
• Acute pain control (procedure)

As of the January 2015 Release, of the concepts above, only Emergency excision of normal appendix (procedure) had |Priority (attribute)| in its concept definition. This was most likely triggered by the word "Emergency" (which is in the value set for |Priority (attribute)|) in the FSN.

Definitions for Surgical Priority

The definitions below are illustrative of the challenge in determining the priority of a surgical procedure (for this example whether it might be might be emergent, essential or elective).
Definitions for Emergent, Essential and Elective Surgery (The Encyclopedia of Surgery, n.d.)

• Emergency surgery

Non-elective surgery performed when the patient's life or well-being is in direct jeopardy.

• Essential surgery

An operative procedure that is considered to be vitally necessary for treating a disease or injury. Postponing or deciding against an essential procedure may result in a patient's death or permanent impairment. May be performed on either an elective or emergency basis.

• Elective surgery 

Surgery that can be scheduled in advance and is not considered an emergency. It may be either medically required (e.g., cataract surgery), or optional (e.g., breast augmentation or implant) surgery. However, some elective surgeries can be considered essential.
It is easy to see how confusion might arise because some essential surgeries can be performed on either an elective or emergency basis and some elective surgeries can be essential.

Concept Definitions

The difficulty in determining whether a procedure should be assigned a priority is illustrated in the examples below.
Example 1: 233370007 |Aortic aneurysm repair (procedure)|
This may be an essential surgery that can, at times, be scheduled as an emergency procedure or as an elective procedure. This concept definition does not include |Priority (attribute)|.


Example 2: 386308007 |First aid (procedure)|
Based on some of the definitions available for first aid, it may be difficult to determine whether a term as basic as "First aid" warrants |Priority (attribute)| and, if so, which value.

Depending on which definitions above is chosen, |First aid (procedure)| could be assigned:

1. Priority (attribute)

   = 25876001

   Emergency (qualifier value)

2. Priority (attribute)

   = 88694003

   Immediate (qualifier value)

3. No priority at all (per the nursing definition of "initial care of a minor injury")

In SNOMED CT, |First aid (procedure)| is modeled as a child of |Emergency treatment (procedure)| from which it inherits |Priority (attribute)| = |Emergency (qualifier value)|.

Example 3: 703985001 |Chest thrust (procedure)|

An additional issue that impacts the usefulness of |Priority (attribute)| is its value set 272125009 |Priorities (qualifier value)|.
Priorities (qualifier value)
Delayed priority (qualifier value)
Elective (qualifier value)
Emergency (qualifier value)
High priority (qualifier value)
Immediate (qualifier value)
Normal priority (qualifier value)
Reclassified (qualifier value)
Reclassified and rescheduled (qualifier value)
Repeat elective (qualifier value)
Repeat emergency (qualifier value)
Rescheduled (qualifier value)
Routine (qualifier value)
Scheduled - priority (qualifier value)
Urgency (qualifier value)
As soon as possible (qualifier value) (added in the July 2015 Release)

Ambiguous values in |Priorities (qualifier value)|

Some of the values for |Priority (attribute)| are ambiguous and the meaning of others may be relative to the procedure they qualify or to the setting/location in which it is done. Therefore, text definitions for many of the values may not be possible.
Example: (From the IHTSDO Content Tracker)
artf222457 - Concept model review: "Routine antenatal care"
A requestor asked that: 134435003 |Routine antenatal care (regime/therapy)| be assigned |Priority (attribute)| = |Routine (qualifier value)|. However, subsequent research suggested that "routine antenatal care" may refer to a standard, rather than a priority: Routine antenatal care involves regular visits by the pregnant patient to healthcare providers, combined with a standard regimen of testing and healthcare interventions that have as a goal the prevention of infant morbidity and mortality.
Thus, the adjective "routine" has a different meaning when applied to antenatal care than when applied to appendectomy.
The three sets of values below represent allowed values for |Priority (attribute)| for which the distinction between the values within each group may be difficult to define or the values in the group may not even represent priorities. Examples of inconsistencies in the use of these values in concept definitions are also provided.

Set 1 - "Non-urgent" Priorities

• Elective (qualifier value)
• Normal priority (qualifier value)
• Routine (qualifier value)

Example:
235313004 |Non-emergency appendectomy (procedure)| has |Priority (attribute)| = |Routine (qualifier value)|

It is not clear whether |Routine (qualifier value)|, |Elective (qualifier value)| or •Normal priority (qualifier value) should be used in this concept definition. Additionally, reviewing the literature, it is difficult to determine the exact meaning of "Non-emergency appendectomy" or whether it is a duplicate for any of the following terms.

1. Interval appendectomy (represented by a separate concept in SNOMED CT)

An appendectomy performed in an elective setting after the acute inflammatory condition from acute appendicitis has subsided. The procedure usually follows successful medical treatment for complicated appendicitis._Interval appendectomy is performed either semi-electively or electively.

1. Elective appendectomy (not represented in SNOMED CT)

A definitive definition is hard to find. Some sources use it interchangeably with interval appendectomy and routine appendectomy. The American College of Obstetricians and Gynecologists refers to Elective coincidental appendectomy - "as the removal of the appendix at the time of another surgical procedure unrelated to appreciable appendiceal pathology."_

1. Routine appendectomy (not represented in SNOMED CT)

_An appendectomy after initial, successful, non-operative management is sometimes referred to as a "routine appendectomy", a "routine interval appendectomy" or an "interval appendectomy"
Some sources distinguish between these procedures and others use them interchangeably. As of the January 2015 Release, 174045003 |Interval appendectomy (procedure)| was defined with 260870009 |Priority (attribute)| = 416774000 |Scheduled - priority (qualifier value)|.

However, in SNOMED CT, the default context for a | Procedure (procedure) | is that it "is actually occurring" or "has occurred". Therefore, the "priority" for an interval appendectomy is no longer "scheduled" once the procedure is actually being done and this is option should not exist for concepts in the |Procedure (procedure)| hierarchy because a scheduled procedure should be a |Procedure with explicit context (situation)|.

Set 2 - "Higher" Priorities

• Emergency (qualifier value)
• High priority (qualifier value)
• Immediate (qualifier value)
• Urgency (qualifier value)
• As soon as possible (qualifier value)

Examples:
182814007 |Emergency dressing (procedure)| has |Priority (attribute)| = |Emergency (qualifier value)|.

439868004 |Direct current ventricular defibrillation (procedure)| does not have |Priority (attribute)|. Again, this is generally illustrative of the when the FSN lacks a term which explicitly states a priority.

The following two concepts do not have |Priority (attribute)| in their concept definitions. Whether they should and which value should be used is somewhat subjective because the site and the extent of the bleeding may affect the priority.

• 698648007 |Control of hemorrhage of intrathoracic blood vessel following vascular surgery (procedure)|
• 310401004 |Packing for postoperative bleeding from tonsillar bed (procedure)|

Substantiating the idea that the distinctions between these values which represent "higher" priorities are not reproducible, The World Society of Emergency Surgery Study Group initiative on Timing of Acute Care Surgery classification states, "Prompt, early, urgent, expeditious, immediate, and emergency are common adjectives used in the medical literature to describe the need for surgery "in a timely manner".
Additionally, in some contexts immediate might refer to a level of 'urgency', whereas in other contexts it might refer to a timeline such as 'straight after'.
Therefore, |Immediate (qualifier value)| and |Delayed priority (qualifier value)| as part of the value set for |Priority (attribute)| may add to the confusion as to whether this attribute addresses true prioritization or merely timing (which at times may reflect prioritization and at times may not.)
Example:
443611007 |Reconstruction of breast with immediate insertion of breast prosthesis (procedure)|
This concept is modeled with |Priority (attribute)| = |Immediate (qualifier value)| and is a subtype of 410533009 | Procedure by priority (procedure) |. However, for this procedure, the term "immediate" is not a matter of priority but rather of timing and simply asserts that the breast prosthesis was inserted at the same time as the breast reconstruction.  

Set 3 - "Repeat" Priorities

• Repeat elective (qualifier value)
• Repeat emergency (qualifier value)

"Repeat" does not have anything to do with prioritization. |Elective (qualifier value)| and |Emergency (qualifier value)| already exist as values for |Priority (attribute)|.

Priorities which Overlap with |288532009 |Context values for actions (qualifier value)|

The following values in |Priorities (qualifier value)| all represent context and would be more appropriate as subtypes of |Context values for actions (qualifier value)| which is the allowed value set for |Procedure context (attribute)| which is an attribute used for |Procedure with explicit context (situation)| concepts.

• Delayed priority (qualifier value)
• Scheduled - priority (qualifier value)
• Reclassified and rescheduled (qualifier value)
• Rescheduled (qualifier value)

Some of these values overlap with values which already exist as |Context values for actions (qualifier value)|.The first concept in each pair below is from |Priorities (qualifier value)| and the second is from |Context values for actions (qualifier value)|.

The SNOMED CT® Editorial Guide January 2015 - Section 6.4.1 states:
Concepts in the | Procedure | and | Clinical finding | hierarchy have a default context of the following:
The procedure has actually occurred (versus being planned or canceled) or the finding is actually present (versus being ruled out, or considered);
The procedure or finding being recorded refers to the patient of record (versus, for example, a family member);
The procedure or finding is occurring now or at a specified time (versus some time in the past).
Context elements typically alter the meaning in such a way that the resulting concept is no longer a subtype of the original concept.
Delayed, scheduled and rescheduled procedures will take place in the future. Thus, their meaning is altered from the default context for a |Procedure| in SNOMED CT and these procedures should be represented in the |Procedure with explicit context (situation)| hierarchy and defined using |Procedure context (attribute)| rather than |Priority (attribute)|.

Regional and Institutional Variation in Procedure Prioritization

The priority of a procedure may be also relative to the specialty or to the region or organization where it is performed. Priority can be determined on the basis of clinical need which may not always be based on who is sickest. It might be based on who will derive the most benefit from treatment as determined by clinical guidelines and evidence based medicine. Sometimes priority may be on the basis of time spent on a waiting list, or for some surgeries (e.g., elective cosmetic surgeries), or in some nations, prioritization may be on the basis of ability to pay or insurance coverage. There are a range of purpose-designed evaluation instruments available for clinical prioritization to assist in ranking patients and determining their eligibility for elective care. Given the variation in procedure prioritization by country, specialty and organization, |Priority (attribute)| may better serve local extensions where its meaning may be able to be more clearly defined.

National Variation in Elective Surgery Urgency Categories

The publication by the Australian Institute of Health and Welfare and the Royal Australasian College of Surgeons _– "National definitions for elective surgery urgency categories" provides some examples of national variations in prioritization of elective surgeries which illustrate that the meaning of the values for |Priority (attribute)| may not be reproducible in all settings.
Examples of variation in surgical prioritization by nation described in the publication include:

Australia

The Australian Institute of Health and Welfare and the Royal Australasian College of Surgeons assigns an urgency level to elective procedures and states, "The urgency category should be appropriate to the patient and their clinical situation, and not influenced by the availability of hospital or surgeon resources."
The definitions of the urgency categories for elective procedures are based simply on the time frame in which the procedure is clinically indicated, as judged by the treating clinician.
Proposed simplified, time-based definitions of urgency categories⁵:

Italy

In 2001, the Italian Ministry of Health funded the Surgical Waiting List Information System project to investigate solutions for managing elective surgery waiting lists. It incorporates urgency related groups and corresponding pre-set maximum time before treatment. It drew on the Australian system as part of its development (Valente et al. 2009). The five urgency categories were adopted based on two criteria: first, fast progression of disease presence and second, the level of pain, dysfunction or disability⁵.

Variation in Surgery Urgency Categories by Specialty

In Ontario Canada, clinicians assess each patient and determine how urgent their need for treatment is. Priority categories I – IV are used to prioritize patients. However, the definitions for the Priority I – IV categories vary by the specialty and procedure performed.
Examples of variation in surgery priority (levels l - lV) for general versus orthopedic surgeries:

Variation in Prioritization of Surgery by Organization

Organizations can also set standards for surgical prioritization. The World Society of Emergency Surgery Study Group initiative on Timing of Acute Care Surgery suggests the following classification system for triage/prioritization of acute care surgery:
Immediate - implies an extreme or markedly decompensated physiological state, usually resulting from bleeding. This is rare in non- traumatic surgical emergencies, and for most bleeding patients initial resuscitative measures will enable further evaluation, diagnosis and even non-operative treatment. Active intra peritoneal bleeding due to a ruptured visceral aneurysm, a ruptured spleen due to hematological disorder with bleeding are examples of a condition that requires immediate surgery. In this category, life or tissue loss is imminent.
Within an hour from diagnosis - implies signs and symptoms of vascular compromise: incarcerated hernia with bowel entrapment, mesenteric vascular occlusion, or limb ischemia. Diffuse peritonitis due to uncontained hollow viscus perforation is another example of a condition that requires surgery "within an hour" as is the presence of necrotizing fasciitis with sepsis. Patients diagnosed with these pathologies need to be adequately resuscitated and managed while undergoing further diagnoses and other steps toward safe surgery. Physiologically, patients may have signs of sepsis or mild to moderate organ dysfunction requiring rapid resuscitation without delaying surgical intervention. In most cases, tissue loss is imminent.
Within 6 hours from diagnosis - implies localized peritonitis or soft tissue infection in need of surgery, but not a physiological state that entails spreading or progression of the disease process. These pathologies have the potential to evolve to more serious conditions if surgery is delayed. Antibiotic treatment and fluid administration should be initiated immediately upon diagnosis and repeat examination carried out while waiting for surgery.
Within 12 hours from diagnosis - implies a need of surgery, though evidence- based knowledge indicates that postponing surgery while under medical treatment does not lead to clinical deterioration. As an example, delay in treatment of acute appendicitis has been shown to have no deleterious effect on outcomes.
Within 24 or 48 hour from diagnosis - Suggests that intervention is indicated and the process may progress and worsen the morbidity of the operation. Examples include cholecystitis and thoracic empyema. The classification also applies to patients who were operated under emergency, and re-laparotomy was decided upon during the index procedure for peritoneal cavity rinsing or for assessment of bowel perfusion and viability.
The scenarios and definitions provided above illustrate the considerable variation in the use of prioritization with respect to procedures and also demonstrate that the variety of priority descriptors extends well beyond the small set of adjectives available as values for |Priority (attribute)|.

SNOMED CT International Request Submission (SIRS) Requests Related to Prioritization of Procedures

There are a number of completed and pending SIRS requests which indicate that there is some user need for content related to procedures that have been pre-coordinated with priority. Some of the requests also illustrate some of the issues related to |Priority (attribute)| which have been presented in this document. They provide another example of how procedures with prioritization may be relative to the procedure, place or the situation and therefore, the meaning may not be interoperable at the international level.

Requests for new |Procedure by priority| content assigned to artf6250 which have been closed

• Crash lower segment caesarian section - Rejected as duplicate for existing concept: |236985002|Emergency lower segment cesarean section (procedure)|)
• Crash classical caesarian section - Rejected as duplicate for existing concept: |274130007|Emergency cesarean section (procedure)|)

Requests for new procedure concepts in SIRS assigned to Priority artf6250:

• Emergency lower segment caesarian section with postpartum sterilization
• Emergency lower segment caesarian section with bilateral tubal ligation
• Elective lower segment caesarian section with postpartum sterilization
• Elective lower segment caesarian section with bilateral tubal ligation
• Emergency classical caesarian section with postpartum sterilization
• Emergency classical caesarian section with bilateral tubal ligation
• Elective classical caesarian section with postpartum sterilization
• Elective classical caesarian section with bilateral tubal ligation

Examples of recent SIRS requests for new content related to Priority (but not tagged as related to artf6250 in SIRS)

Requests for new |Procedure by priority| content for possible addition in Jan 2016

• Crash lower segment caesarean section in first stage of labor (procedure)
• Crash lower segment caesarean section in second stage of labor (procedure)

New content related to Priority which has been recently added

• Emergency contraception done (situation) - Released July 2014 but added as Prescription of emergency contraception done (situation).
• Routine gynecological exam done (situation) - Released July 2014
• Routine gynecologic examination (procedure) - Released July 2014

Requests for changes to existing |Procedure by priority| content but not tagged as artf6250 in SIRS

• Admit pediatric emergency (procedure) – This existing concept's FSN was changed to Pediatric emergency hospital admission (procedure) in May 2015 because the submitter suggested that the initial wording implied an imperative rather than a procedure
• A total of 29 similar FSN name changes were made for the July 2015 Release

Requests related to |Priorities (qualifier value)| (the value set for Priority)

These requests support the idea that there may be some user confusion/concern about the meaning of the values.

• Request Id 423234 - Normal Priority vs Routine
  • Request - "These two terms seem redundant with Normal Priority not very descriptive. It is requested to retire Normal Priority (394848005) and make it a synonym for Routine (50811001)."

The SNOMED CT modeler and the requestor engaged in a dialogue which indicated they had different interpretations of the meaning of the two terms and of whether they were synonymous in the context of procedure priorities.

• Request Id 23235 – Retire: Rescheduled Priority
  • Request - "It is unclear how rescheduled is a priority. Rescheduled seems to be an action that is attempting to communicate something, but it is unclear how this would figure in a priority. Rescheduled might go under a general descriptor?"
• Request Id 389968 – Add: |As soon as possible (qualifier value)|
  • Justification: Assist with alignment of HL7 (table 0027 version 2.8) value sets with SNOMED CT

Requests that illustrate the potential for combinatorial explosion for procedures

These SIRS requests are included to illustrate an additional issue related to |Priority (attribute)| which relates to whether pre-coordination of procedure prioritization should be excluded in the International Release due to the potential for combinatorial explosion (e.g., some of these requests are for procedures with prioritization as well as additional context such as the reason for the procedure, outcome, etc.). They highlight the ongoing challenge of determining what should be represented in the terminology model and what should be represented in the information model.

• Routine gynecological exam done (situation) (includes priority-procedure-status)
• Routine general medical exam order for laboratory test done (situation) (includes priority-procedure-focus-status)
• Routine eye and vision examination with abnormal findings done (situation) (incudes priority-procedure-outcome-status)
• Elective sterilization counseling done (situation)
• History of cardiac device in situ with elective replacement indicator previously removed (situation)
• History of elective breast augmentation (situation) - Added in July 2015
• History of elective reduction of breast (situation) - Added in July 2015

The last two concepts above raise the issue of whether these two surgeries are ever not elective surgeries and whether there is truly a distinction between each of these two new concepts and their parent.
Example:

Subsidiary and interrelated problems

Decisions related to the criteria for the inclusion of |Procedure by priority| concepts in SNOMED CT may also impact concepts which take |Procedure| as a value in their concept definitions.
In particular, this may impact concepts in the:

1. Procedure with explicit context (situation)

   hierarchy for which

   Procedure

   is the value set for

   Associated procedure (attribute)

   .

Example:

=== 443938003 |Procedure carried out on subject (situation)| :
{ 363589002 |Associated procedure (attribute)| = 702584003 |Counseling for elective sterilization (procedure)|,
408731000 |Temporal context (attribute)| = 410512000 |Current or specified time (qualifier value)|,
408730004 |Procedure context (attribute)| = 385658003 |Done (qualifier value)|,
408732007 |Subject relationship context (attribute)| = 410604004 |Subject of record (person)| }

1. Procedures for which another |Procedure| is the value for 363702006 |Has focus (attribute)|

Example:
702584003 |Counseling for elective sterilization (procedure)| would be sufficiently defined:
=== 409063005 |Counseling (procedure)| :
363702006 |Has focus (attribute)| = Elective sterilization (procedure) (does not currently exist),
260686004 |Method (attribute)| = 129441002 |Counseling - action (qualifier value)|
Therefore, policy regarding inclusion of |Procedure by priority| concepts should extend to |Procedure with explicit context (situation)| concepts that reference a |Procedure by priority| and to |Procedure| concepts with a focus of another |Procedure by priority| concept. This interdependency will be addressed in the guidance provided in Section 6.1.1.1.

Risks / Benefits

Risks of not addressing the problem

Attributes that do not meet URU criteria create a false sense of security for users particularly for content which is sufficiently defined using these attributes. Users cannot rely on this content for retrieval or in equivalency testing. New procedures that have explicit or implicit prioritization according to various standards will continue to be requested. Whether these procedures should be added or are ambiguous will need to be assessed on a case by case basis. However, even if the procedures are added, continuing to define them using |Priority (attribute)| will expand the scope of the current problem.

Risks of addressing the problem

Addressing the problem may result in the elimination or constrained use of |Priority (attribute)| and its value set. This may mean that some content which previously appeared to be able to be sufficiently defined can no longer be sufficiently defined and this may seem to be a setback to the going effort to sufficiently define content in SNOMED CT. Without a clear understanding of the reasons for the changes, some users may feel that these constraints limit their ability to retrieve some content and to create definitions in their extensions and post-coordinated expressions.

Requirements: criteria for success and completion

Criteria for success/completion

Consistent meaning, modeling and editorial policy

The criteria for success/completion for this project will be:
To address the issues outlined in this document with respect to the failure of |Priority (attribute)| to meet URU criteria and to provide definitive guidance for the disposition of |Priority (attribute)| in pre-coordinated and post-coordinated content.
To provide clear editorial guidance for the inclusion of new |Procedure by priority| content (which may still be valid in SNOMED CT regardless of whether it can be sufficiently defined).
To review all concepts with concept definitions that currently include |Priority (attribute)|, or which have explicitly stated priority in their FSN, for validity.
To remove |Priority (attribute)| from concept definitions and, where appropriate, assert stated IS_A relationships to replace any correct relationships which were previously inferred by the classifier for sufficiently defined concepts.
To provide guidance for the existing value set for |Priorities (qualifier value)| and to retire inappropriate values.

Strategic and/or specific operational use cases

Clear editorial policy development for |Procedure by priority| content

Editorial policy guidance for inclusion criteria and for the Concept Model for |Procedure by priority| content in the |Procedure (procedure)| and the |Procedure with explicit context (situation)| hierarchies to will help to ensure the integrity of SNOMED CT content in order to meet the expectations and needs of users.

Fit with IHTSDO strategy

A sound and valued primary product [SNOMED CT] – Editorial policy for |Procedure by priority| content that is clear and supports the development of unambiguous content is critical to achieving a quality product that allows users to understand; 1. The type of content they can expect to find in SNOMED CT. 2. The meaning of the content when used in the HER. 3.The limitations of the content with respect to retrieval and equivalency detection.

Solution Development

Initial Design

Outline of initial design

Major design changes and their justification are summarized in the sections below. Within each section, the specific design change suggestion can be found in the Recommendation section.
The steps in the initial design include providing:

1. Exclusion and inclusion criteria for Procedures categorized by priority
2. Modeling guidance for Procedures categorized by priority
3. Guidance for 260870009 |Priority (attribute)|
4. Guidance for the 272125009 |Priorities (qualifier value)| value set

Exclusion and inclusion criteria for Procedures categorized by priority

As described in Section 3.4.4 of this document, there are significant regional, institutional and organizational variations in the definitions for Procedures categorized by priority.
The ambiguity related to Procedures categorized by priority is similar to the ambiguity for Procedures categorized by complexity. Exclusion and inclusion guidance is already provided in the July 2015 Editorial Guide Section 3.4.4.4 for Procedures categorized by complexity which states:
Procedure concepts that include modifiers that represent procedure complexity based on the amount of effort required, or based on realm-specific definitions, are not to be added to the international release.
Examples of prohibited concepts:
Simple arthrodesis, simple repair, complex repair.
This policy does not proscribe the additions of procedures that use the words "simple" or "complex" which are defined by reproducible meanings based on what is done to or for the patient, rather than how much effort is expended in doing it.
Example of acceptable definition:
Simple mastectomy: Reproducibly defined as the removal of all breast tissue without removal of axillary contents. Differentiated from modified radical, radical, skin-sparing, and subcutaneous variants of mastectomy.

Recommendation for inclusion and exclusion guidance for Procedures categorized by priority

Suggested guidance for inclusion and exclusion guidance for Procedures categorized by priority (which is similar to guidance for Procedures categorized by complexity) includes:
Procedure concepts that include modifiers that represent procedure priority based on regional, or institutional definitions should not be added to the International Release unless clear, text definitions can be provided which have international interoperability.
This policy does not prohibit the addition of procedures by priority which have interoperable meaning at the international level based the conditions that define their prioritization.
Example of an acceptable concept and definition:
Emergency caesarian section – A caesarian section done urgently either for the health of the mom or the fetus.
If this is a generally accepted definition for the condition under which an emergency caesarian section is performed, the concept can be added. This is regardless of whether the procedure is done in technically the same way as the non-prioritized procedure.
Additionally:

• <Procedure X> with <priority> (procedure)

  should not be added if the prioritization is already understood or implicit in

  <Procedure X> (procedure)

  (e.g., the only way that

  <Procedure X> (procedure)

  is performed is with the prioritization requested).

Example:
Elective breast augmentation should not be added if breast augmentation is always an elective procedure. Thus, since 22890008 | Augmentation mammoplasty (procedure) | already exists in SNOMED CT, Elective augmentation mammoplasty or Elective breast augmentation should not be added.

• History of <procedure X> with <priority> (situation)

  should not be added if the prioritization is already understood or implicit in

  History of <procedure X> (procedure)

Example:
15071000119107 | History of elective breast augmentation (situation) | should not be added If 427894009 | History of augmentation of breast (situation) | already exists and a breast augmentation is always an elective surgery.

• <Procedure X> with <priority> and <outcome> (procedure)

  represents excessive pre-coordination and should not be added.

Example:
174039006 | Emergency excision of normal appendix (procedure) | - It appears that this procedure was intended to represent an appendectomy that was done emergently but, in retrospect, may not have had to be done emergently because the outcome was a normal rather than a diseased appendix. However, this is combining a procedure and a finding (which can only be determined intraoperatively or postoperatively) and this should not be pre-coordinated.
The same guidance should apply for |Procedure with explicit context| (e.g., Routine eye and vision examination with abnormal findings done (situation)| should not be added.

Recommendation for existing Procedure categorized by priority concepts

The existing subtypes of |Procedure by priority (procedure)| (there were 191 in January 2015) should be reviewed to verify that they are valid concepts with unambiguous meaning. Additionally, |Procedure| concepts (and |Procedure with explicit context|) concepts with prioritization asserted in their FSNs (based on lexical variations of the final value set for |Priorities (qualifier value)|) should be reviewed for ambiguity and redundancy and retired if necessary.

Modeling guidance for Procedure categorized by priority concepts

For procedures that meet inclusion criteria, additional modeling guidance is provided including:

Recommendations for breadth of coverage for Procedures categorized by priority

1. If |<Procedure X> with <priority> (procedure)| is valid to be added to SNOMEC CT, then |<Procedure X> (procedure)| should be also be added.

Example:
If Emergency lower segment caesarian section with bilateral tubal ligation (procedure) is added, Lower segment caesarian section with bilateral tubal ligation (procedure) should also be added if it does not already exist.

1. <Procedure X> with <priority> (procedure)

   should be added prior to other procedure or situation concepts that reference

   <Procedure X> with <priority> (procedure)

   as a value (e.g.,

   History of <Procedure X> with <priority> (procedure)

   or

   Counseling for <Procedure X> with <priority> (procedure)

   .)

Example:
702584003 |Counseling for elective sterilization (procedure)| was added to SNOMED CT. However, Elective sterilization (procedure) does not yet exist in SNOMED CT.
Prior to the addition of 702584003 |Counseling for elective sterilization (procedure)|, it should be considered whether the concept offers anything not already provided by the existing concept 702583009 |Counseling for sterilization (procedure)|. For example, is any sterilization (even compulsory sterilization) not considered to be elective?
If the decision is made to add |Counseling for elective sterilization (procedure)| as a new concept, the procedure for which the counseling is being offered (e.g., Elective sterilization) should also exist in SNOMED CT.
This guidance is prudent because:

• Generally, |<Procedure X> (procedure)| will be used more in a record than |<Procedure X> with <priority> (procedure)|.
• Generally, |<Procedure X> with <priority> (procedure)| will be used more than concepts referencing |<Procedure X> with priority (procedure)| (e.g., |History of <Procedure X> with priority (procedure)| or |Counseling for <Procedure X> with priority (procedure)|).
• The more general concepts (e.g., |<Procedure X> (procedure)| and |<Procedure X> with priority (procedure)|) will provide values that allow the more complex variations (e.g., |History of <Procedure X> with priority (procedure)|) to be sufficiently defined.

Recommendations for modeling existing Procedures categorized by priority concepts

Because the recommendation in Section 6.1.1.3 below advocates for the removal of |Priority (attribute)| from concept definitions in the International Release, the limited number of existing concepts which are currently sufficiently defined using this attribute will need to be made primitive and some stated Is_a relationships will need to be asserted for appropriate hierarchical relationships currently inferred by the classifier.

Guidance for 260870009 |Priority (attribute)|

As established in Section 3 of this document, the objective of meaningfully defining and classifying procedures using 260870009 |Priority (attribute)| fails URU criteria for reasons that include:

• Priority

  in the context of procedures is often subjective and often lacks reproducible definitions due to regional, institutional and organizational variations.

• Existing content modeled with |Priority (attribute)| has errors of commission (e.g., is modelled inconsistently).
• Existing content that appears to be clearly warrant |Priority (attribute)| is lacking the attribute and the potential scope of procedures that might require review for addition of the attribute is significant and cannot be easily queried for.
• The 272125009 | Priorities (qualifier value) | value set has ambiguities, is incomplete and covers some axes which are not true priorities. Definitions for the values may be difficult to provide because their meaning is relative to the procedure they qualify.
• Sometimes a priority, which actually refers to the patient, may be reflected in the procedure for that patient as a matter of convenience (e.g., a patient without insurance may have a lower priority for an elective procedure than an insured patient).

Refining editorial guidance to meet the URU criteria required to sustain semantic interoperability for |Priority (attribute)| does not seem to be a feasible task in the short term and is likely to be a difficult, if not unattainable, task in the long term. On this basis, and because the attribute does not achieve the objective of meaningfully defining and classifying procedures by prioritization, it is recommended that use of |Priority (attribute)| be discontinued in the SNOMED CT International Release.
However, there appears to be a need to identify priority to support case management along the patient pathway as evidenced by the definitional work related to priority at the nation and organizational level. It is possible that some procedures by priority and the | Priorities (qualifier value) | value set could be defined at a local level in an understandable and reproducible way that would allow consistency. Therefore, the attribute may still be useful at the regional or institutional level in post-coordination. For this reason, it is suggested that guidance for this attribute should be similar to the guidance the July 2015 Editorial Guide Section 6.1.2.7. for |Severity (attribute)| which states:
This attribute is used to subclass a | Clinical finding | concept according to its severity; however, caution is encouraged because this use is said to be relative. By relative, it is meant that it is incorrect to assume that the same degree of disease intensity or hazard is implied for all | Clinical finding | to which this attribute is applied. There are three reasons.First, "severe" could be interpreted differently depending on what other values are available to choose for severity. Thus severity is relative to the other values in the value set presented to users. Consider the different meaning of severity in each of the following three sets of values:

• mild / moderate / severe
• minimal / mild / moderate / severe / very severe
• mild / mild to moderate / moderate / moderate to severe / severe / life threatening / fatal

Second, the severity is defined relative to the expected degree of intensity or hazard of the | Clinical finding | that is being qualified. A common cold has a baseline intensity or hazard much less than that of a more serious disease like lupus erythematosus or pneumonia; thus a severe cold might be considered less intense or hazardous than a mild pneumonia.
Third, some disorders that are life-threatening do not ordinarily have a severity assigned to them. Cancer, for example, is generally not subclassed according to mild, moderate and severe types, but rather is subclassed according to stage or grade.
For these reasons, the | SEVERITY | attribute cannot be relied on to retrieve all Clinical findings with serious or life-threatening import. Nevertheless, it is still useful for sub classing certain concepts and differentiating between different severities of a single disorder. SEVERITY is not used to model any concepts pre-coordinated in the International Release but it can still be used in post-coordination as a qualifier.

Recommendations for Editorial Guidance on 260870009 |Priority (attribute)|

This attribute is used to subclass a |Procedure| concept according to its priority. However, caution is advised because this use is felt to be relative in that it is incorrect to assume that the same degree of prioritization is implied for all |Procedure| concepts to which this attribute with a specific value is applied.
The reasons for this guidance include:

1. "Prioritization" can be interpreted differently depending on what other values are available to choose for priority. Thus priority may be relative to the other values in the value set presented to users. Consider the different meaning of priority in the following two sets of values:

• Elective / As soon as possible / High priority
• Elective / As soon as possible/ High priority / Emergency

In the first value set, |High priority| might indicate the most urgent of the priorities, however in the second value set that is no longer true. Thus, the meaning of 394849002 |High priority (qualifier value)| when applied to a procedure may shift relative to the value set within which it is interpreted.

1. The meaning of the value assigned to |Priority (attribute)| is defined relative to the |Procedure| that is being qualified. The meaning of 25876001 |Emergency (qualifier value)| when assigned as a prioritization for a dental procedure may be entirely different that the meaning when applied to a cardiac procedure. The implication of a delay for the dental procedure may be much less than for the delay of a more serious procedure such as the repair of aortic aneurysm. Thus, an emergency dental procedure would most likely have lower priority than an emergency repair of aortic aneurysm, even if both are assigned the same priority.

1. Some procedures that are essential or emergent to treat life-threatening disorders do not necessarily have a stated priority assigned to them. For example, procedures like |Repair of rupture of coronary artery (procedure)| are generally not subclassed according to their priority. Even for procedures where prioritization is implied by the very nature of the procedure, the level of prioritization may have a subjective component.

For these reasons, |Priority (attribute)| cannot reliably retrieve and classify subtypes of |Procedure by priority (procedure)|. Therefore, is not used to model concepts pre-coordinated in the International Release. However, |Priority (attribute)| can still be used in post-coordination as a qualifier where it may be useful for subclassing certain procedures in a specific surgical domain or in a regional or institutional setting where prioritization can be differentiated based on specific definitions that can be consistently applied.

Guidance for the 272125009 |Priorities (qualifier value)| value set

Regardless of whether the |Priority (attribute)| is retained in the International Release or constrained to use as a qualifier in post-coordination, the 272125009 |Priorities (qualifier value)| value set should be reviewed for inappropriate values.
Subtypes of Priorities (qualifier value) (as of the July 2015 Release)
Delayed priority (qualifier value)
Elective (qualifier value)
Emergency (qualifier value)
High priority (qualifier value)
Immediate (qualifier value)
Normal priority (qualifier value)
Reclassified (qualifier value)
Reclassified and rescheduled (qualifier value)
Repeat elective (qualifier value)
Repeat emergency (qualifier value)
Rescheduled (qualifier value)
Routine (qualifier value)
Scheduled - priority (qualifier value)
Urgency (qualifier value)
As soon as possible (qualifier value) – added in the July 2015 Release

Recommendations for the 272125009 |Priorities (qualifier value)| value set

1. 64695001 |Repeat elective (qualifier value)| and 21282002 |Repeat emergency (qualifier value) should be retired as 363661006 |Reason not stated concept (inactive concept)|.

(These concepts are not used in any concept definitions in the July 2015 Release.)
As discussed earlier in the document, "Repeat" does not have anything to do with prioritization. |Elective (qualifier value)| and |Emergency (qualifier value)| already exist as values for |Priority (attribute)|.

1. Values which overlap with 288532009 |Context values for actions (qualifier value)| should be retired.

As discussed earlier in the document, the following values in |Priorities (qualifier value)| represent context and belong in the value set |Context values for actions (qualifier value)| which is the allowed value set for the attribute |Procedure context (attribute)| which is used to model |Procedure with explicit context (situation)| concepts.

1. 1. Retire 416774000 |Scheduled - priority (qualifier value)| as Ambiguous concept - Possibly equivalent to 416151008 |Scheduled - procedure status (qualifier value)|.

(This concept is used in two concept definitions in the July 2015 Release.)

1. 1. Retire 58334001 |Rescheduled (qualifier value)| as Ambiguous concept - Possibly equivalent to a new concept (to be added) called |Rescheduled - procedure status (qualifier value)| which would be a subtype of 385649005 |Being organized (qualifier value)| and a sibling of 416151008 |Scheduled - procedure status (qualifier value)|.

(This concept is not used in any concept definitions in the July 2015 Release.)
This seems preferable to retaining |Rescheduled (qualifier value)| and making it a subtype of 385649005 |Being organized (qualifier value)| because users may have already been using |Rescheduled (qualifier value)| for a different purpose because of the value set it was allowed for. For that reason, it seems safer to retire it and replace it with a new concept.

1. 1. Retire 441808003 |Delayed priority (qualifier value)| as Ambiguous concept - Possibly equivalent to 385642001 |Under consideration (qualifier value)|.

(This concept is not used in any concept definitions in the July 2015 Release.)

1. Retire 76561005 |Reclassified (qualifier value)| and 44408006 |Reclassified and rescheduled (qualifier value)| as 363661006 |Reason not stated concept (inactive concept)|.

(These concepts are not used in any concept definitions in the July 2015 Release.)
It is difficult to know the origin of | Reclassified (qualifier value) |. A brief literature review does not readily reveal specific procedures which are modified by the qualifier "reclassified". However, it is possible that this concept originated because patients awaiting surgical procedures are sometimes classified on the basis of their surgical risk and may be considered too high risk for surgery. If they are reclassified on the basis of their surgical risk factors, the reclassification could lead to a change in their prioritization for surgery. It is possible that |Reclassified (qualifier value)| and |Reclassified and rescheduled (qualifier value)| were added as a value for |Priorities (qualifier value)| for this reason. However, even in that scenario, these are still not valid values for prioritization. It is suggested that in the absence of feedback to the contrary, these value be retired as Reason not stated.

1. Remaining subtypes of |Priorities (qualifier value)| (if suggestions 1-3 above are implemented):

• Elective (qualifier value)
• Emergency (qualifier value)
• High priority (qualifier value)
• Immediate (qualifier value)
• Normal priority (qualifier value)
• Routine (qualifier value)
• Urgency (qualifier value)
• As soon as possible (qualifier value) – added in the July 2015 Release

Although there may be overlap and ambiguity in the meaning of these values when used in the International Release (discussed in Section 3.4.3.1), they may be valid and have a specified meaning at the regional or institutional level. It is suggested that the existing values could remain in the International Release (as was done for 272141005 | Severities (qualifier value) | the value set for 246112005 | Severity (attribute) |). The utility of adding new subtypes of |Priorities (qualifier value)| in the International Release may be questionable. However, it is possible that some users will post-coordinate |Procedure with priority| concepts and may not have an extension in which to create new values for priorities. This could be a limitation on their ability to create post-coordinated expressions for procedures with priority. For this reason, it is suggested that new values be added to Priorities (qualifier value) on a case by case basis (e.g., they apply to prioritization of procedures rather than to |Procedure with explicit context|.)

Significant design or implementation decisions / compromises

The significant design implications for this project include:

1. Impact to users of constraining the use of |Priority (attribute)| so that it is no longer used as a defining attribute for pre-coordinated expressions but is still allowed as a qualifying relationship for post-coordinated expressions.
2. If use of the attribute is no longer allowed in the International Release but still allowed as a qualifier in post-coordination, equivalence detection between pre-coordinated and post-coordinated expressions will not be reliable because pre-coordinated content will not include |Priority (attribute)| whereas post-coordinated expressions will use |Priority (attribute)|. While this may be suboptimal, without consistent semantics with respect to the procedure FSNs and the value set for |Priority (attribute)|, the use of |Priority (attribute)| in sufficiently defining content in the International Release does not meet quality assurance criteria which may be even more suboptimal for end users.

Evaluation of Design

Criteria used to evaluate the design(s) are largely described in the criteria for success/completion of the project overall. They include; 1. Providing definitive guidance for the disposition of |Priority (attribute)| in pre-coordinated and post-coordinated content, 2. Providing clear editorial guidance for the inclusion and exclusion of new |Procedure by priority| content in SNOMED CT, 3. Reviewing all concepts with concept definitions that currently include |Priority (attribute)| and adding stated Is_a relationships to replace any correctly inferred relationships previously generated by the classifier, 4. Providing guidance for the existing value set for |Priorities (qualifier value)| and to retire inappropriate values.

Design Strengths

The design removes an attribute which fails URU criteria from the International Release but still allows for the addition of unambiguous |Procedure by priority| content in SNOMED CT.
The design provides users with a clear explanation for why |Priority (attribute)| was removed from the International Release and provides examples of the potential for ambiguity related to prioritized procedures at the international level.
The design retains the option for users to use |Priority (attribute)| in an extension or in post-coordinated expressions.
The design refines and retains the value set |Priorities (qualifier value)| in the International Release and allows users who lack extensions (and are only able to create post-coordinated expressions) access to the necessary concepts to create post-coordinated procedures with priority.

Design Weaknesses

The design does not provide a means to sufficiently design |Procedure by priority| concepts thereby reducing the probability equivalency detection and increasing the reliability on manual assertion of subtypes.
The design shifts responsibility for development of |Procedure by priority| concepts to the user.

Design Risks

Iteration One

Outline of revised design

Redesign the Solution Identify objectives of iteration, and the major changes to previous design
Communicate the revised design
TBD at later time?

Significant design or implementation changes

Evaluation of Revised Design

Exceptions and Problems

Design Strengths

Design Weakness

Design Risks

Recommendation

Detailed design final specification

To avoid duplication of information, the detailed design recommendations are included in each subsection of Solution Development (Section 6) and prefaced with "Recommendation".

Iteration plan

Quality program criteria

Quality metrics

Quality metric 1

Documented and maintained editorial guidance for pre-coordinated and post-coordinated |Procedure by priority| content.

Quality metric 2

Removal of the |Priority (attribute)| from all concepts and assert stated IS_A relationships to replace any correct relationships which were previously inferred by the classifier for sufficiently defined concepts.
Quality metric 2

Quality metric 3

Adherence of new |Procedure by priority| content to inclusion guidelines
Quality metric 3

Project Resource Estimates

Estimate of project size:

Editing

Project size should be limited to procedures which are subtypes of |Procedure by priority (procedure)| (191 in January 2015) or which explicitly assert prioritization in the FSN. (For a better idea of scope, a query is needed for all |Procedure| concepts (and |Procedure with explicit context|) concepts with prioritization asserted in their FSNs based on lexical variations of the final value set for |Priorities (qualifier value)|). Preliminary review suggests that there should be less than 100-200 additional concepts which explicitly assert prioritization in the FSN and are not already subtypes of |Procedure by priority (procedure)|.
Given that detection of procedure concepts where prioritization is not explicitly stated cannot rely upon consistent characteristics/properties, detection of occult 'prioritization' would be a very time consuming activity. Therefore, procedures for which prioritization may be implied (e.g., |Repair of rupture of coronary artery (procedure)|) but not explicitly stated, will be considered out of scope.
The editing project should be limited to; 1. Evaluating the in scope procedures for validity. 2. Removal of |Priority (attribute)| from concept definitions. 3. Changing the concept definition statuses from Sufficiently defined to Primitive. 4. Manually asserting stated Is_A relationships for valid, previously inferred Is_A relationships. 5. Retiring seven subtypes of |Priorities (qualifier value)|.

Providing guidance for Procedures by Priority for the Editorial guide

Preliminary guidance has been provided in Section 6 of this document. Estimates for completing the guidance will vary according to the degree to which this guidance/project is approved.

Scope of construction phase

Skills required:
A solid understanding of the SNOMED CT Concept Model and Editorial Policies as well as a clinical background and the ability to edit content in an IHTSDO editing tool.
Solution Specification (Elaboration)
Implementation
Outline of work packages
Preventing recurrence of problem
Division of project into stages

Projection of remaining overall project resource requirements

Expected project resource requirement category

This is not a fast track project. The project resource requirement is classed as SMALL – less than 1 person year (most likely less than 3 person months).

Expected project impact and benefit

The project impact on the terminology is expected to be LOW - confined to the limited number of |Procedure| and |Procedure with explicit context (situation)| concepts which explicitly reference a procedure priority. The project impact on users is more difficult to gauge but is felt to be LOW to MEDIUM based on user submissions to SIRS. Benefits are already addressed in Sections 4 and 5.1.

Indicative resource estimates for construction, transition and maintenance:

Elaboration phase: Up to one additional FTE month effort (this is a combined inception/elaboration document so it is not clear whether this information needs to be provided)
Construction and transition phase: Estimate is that 200-300 concepts are currently defined using |Priority (attribute)| and/or contain explicit prioritization in the FSN. The most time consuming aspect of the project will be evaluating the in scope procedures for validity/duplication. At 10 concepts/day this could represent a 1-2 month FTE effort.
Maintenance phase: Difficult to gauge, but based on prior SIRS requests should be <20 new requests per release cycle.