JIRA: https://projects.jira.snomed.org/browse/IHTSDO-314

Document review: 

Amendment History

Review Timetable

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Glossary

Domain Terms

Introduction

Purpose

The purpose of this project is to consider content and modelling issues related to existing and newly requested SNOMED CT concepts following the pattern "Presence of X."
This document combines the documentation of the Inception and Elaboration Phases. The Inception Phase focuses on understanding the problem and its scope, identifying stakeholders and their requirements, and identifying risks. The purpose of the Elaboration Phase is to develop, document and test one (or more) possible technical solutions, and to reach a recommendation and provide a detailed specification of a preferred solution to be taken forward to the construction phase.

Audience and stakeholder domain

The audience for this document includes all standards terminology leaders, implementers and users, but it is especially targeted at the community of SNOMED CT authors that may be requested to implement the recommended specification. The content of this document may also be relevant to request submitters from National Release Centres as well as those clinicians or implementers who utilize SNOMED CT for recording patient data within clinical information systems.

Input from stakeholders

Many requests for SNOMED CT concepts following the pattern, "Presence of X" (or very similar patterns), have been received. As of September 2015, there are at least 39 requests for content that follow this or a similar pattern within the IHTSDO SNOMED CT International Request Submission (SIRS) system. While this may not seem to be a large number, these types of requests continue to be received and are related to larger content issues within SNOMED CT. For these reasons, it would be beneficial to evaluate this issue for the SNOMED CT authors who address these requests as well as and to seek input from them regarding any potential solution, particularly in relation to any difficulties they have been experiencing to date with this type of content.
Feedback received to date includes a brief discussion with a Consultant Terminologist who pointed to a presentation on the Observables and Investigation Procedures Redesign work which addresses Presence/Absence of X content (artf6283).  The presentation proposed an observables conformant approach to representing the presence/absence of observation results, including surgically created structures, therefore directly relevant to this current project.
Further discussion with IHTSDO editors regarding the approach suggested as an interim measure to scope the project to management of requests within the current concept model and the production of terming guidance to standardize this was well received. Though they did not see the detailed terming/modelling guidance presented in this paper.  They also agreed it was important that the project ensured any recommended disposition would carefully consider the larger associated projects and not have an adverse impact upon them. 

Degree of consensus on the statement of problem

The degree of consensus on the statement of problem is currently unknown because this content issue is related to multiple large-scale projects currently under development within SNOMED CT. The degree of consensus regarding the problem as well as relevant solutions will depend on the related projects. This document aims to provide background information related to this content project, define the problem, outline specific modelling issues, identify associated large scale projects, and provide solutions which can be implemented in the near future while awaiting the outcomes and dependencies of the larger content projects.

Statement of the problem or need

Summary of problem or need, as reported

As stated in the IHTSDO CollabNet tracker description for artf222786 : Concept model: Presence of X (situation) - presence of X (finding):
https://csfe.aceworkspace.net/sf/go/artf222786?qkSrchApp=objectId
"Requests for "Presence of X (situation)" where X is either an implanted device (e.g. Presence of shoulder joint replacement (situation)) or else a surgically created anatomical structure (e.g. Presence of urostomy (situation))
The 'accepted' working approach dictates that the presence of 'normal' structures or functions are findings, while the outright statement of presence of abnormal structures or findings (as opposed to just naming them) would be treated as situations, with a context of "known present." Laboratory findings when 'present' are also findings. Though the rationale by which a "Clinical finding present" is a situation while "Laboratory findings present" is a finding is based on an assumption that the laboratory findings name things not normally present (e.g. abnormal cells), which isn't universally the case (some name things normally present, or in quantities/ranges that are normal)."

Summary of requested solution

As stated on the IHTSDO CollabNet tracker for artf222786:
"Solutions should take account of the newer definition of situation (period of the subject's life in which a condition is present), and condition (a structure, process or disposition); and separately take account of the newer definition of observation results, into which many laboratory findings will fit."

Statement of problem as understood

Requests for content following the patterns "Presence of X" and "X present" continue to be received and require modelling guidance. While there has been a working modelling approach to address this content, existing content does not follow the approach consistently. In addition, new requests for specific types of "Presence of X" and "X present" content related to devices and surgically created anatomical structures present modelling challenges such that the working approach cannot be easily implemented. Furthermore, there are large-scale content projects currently under development within SNOMED CT that will likely impact how this content will be addressed once those projects are completed. The expectation is that usable editorial guidance will be produced for "Presence of X" content in relation to devices and surgically created anatomical structures. This guidance would result in consistent content development in these areas, also meeting the needs of the current requesters pending the outcome of larger associated content projects.

Detailed analysis of reported problem, including background

The following topics will be addressed in this section:

• Review of background information: Existing SNOMED CT editorial policy, SIRS requests, and existing content following the patterns "Presence of X" and "X present" (Section 3.4.1)

• Review of specific content areas that present challenges for modelling (Section 3.4.2)

• Review of larger content projects currently under development within SNOMED CT and their relevance to (and dependency for) this artefact (Section 3.4.3)

Background

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Survey of Existing Content
A search of the July 2015 International Release yielded a fair number of existing concepts with "presence" or "present" in fully specified names (FSNs) and descriptions across the clinical finding, situation with explicit context, and observable entity hierarchies. The table below lists the number of related concepts found in each hierarchy; the majority of the content is located within the clinical finding hierarchy and is related to laboratory content. The list of concepts for each set of results can be found in a spreadsheet associated with this project: artf222786_PresenceOfX_Concepts_Combined_Inception_Elaboration_Phase_v0.1.xlsx

Detailed analysis of the problem

This section will provide a more detailed review of specific content issues and challenges related to this artefact.

Existing content modelling inconsistencies

While some existing content does follow the working modelling approach, there are a number of instances of inconsistencies. For example, the current working approach recommends that content following the pattern "Presence of <abnormal structures or findings>" should be modelled as situation with explicit context concepts, however, the concepts listed below are found in the clinical finding hierarchy:

• 302111002 | Ileostomy present (finding)

• 307699005 | Nystagmus present (finding)

• 162236007 | Weakness present (finding)

• 274825006 | Ptosis present (finding)

• 301920009 | Enophthalmos present (finding)

• 302113004 | Urostomy present (finding)

• 164274003 | On examination - stridor present (finding)

In addition, some content can also be found in the observable entity hierarchy. While these concepts were likely created to encode data elements within clinical questionnaires or forms, when these types of concepts are encountered in search results, their use case may not be immediately apparent to implementers:

• 284089007 | Presence of orthopedic joint implant (observable entity)

• 428395000 | Medical identification bracelet present (observable entity)

• 278652005 | Tooth presence (observable entity)

Presence of device / Device present / Device in situ content

"Presence of <device>" and "<Device> present" concepts are likely used to assert that a device is present in the subject of record. Most of this content is located in the 397578001 | Device in situ (finding) hierarchy. Based on the modelling and descriptions of existing concepts, the terms "presence of device" and "device present" appear to be synonymous with "device in situ" in SNOMED CT. As of the July 2015 International Release, there are 58 concepts in this sub-hierarchy (and there may be other existing concepts that should be in this sub-hierarchy, but are not). In addition, there are multiple new requests for similar concepts in SIRS. (Please see Appendix A for SIRS requests and Appendix B for a list of existing Device in situ (finding) concepts.)
Since the presence of a device would not be considered a normal finding or structure, according to existing guidance, it is expected that this content would be in the situation with explicit context hierarchy. However, as shown in the table below, this content has been added in the clinical finding hierarchy, specifically as subtypes of 397578001 | Device in situ (finding). This is likely because current editorial policy does not allow <physical object> concepts as values for the ASSOCIATED FINDING attribute in the situations with explicit context hierarchy concept model. Therefore, modelling this content in the situations hierarchy presents a significant challenge. Modelling recommendations for this content will be addressed in Section 6 of this document.

Presence of surgically created anatomical structure content

In a similar way to devices, surgically created anatomical structures, which are acquired body structures created as a result of an operative procedure, would also not be considered "normal findings."
Within SNOMED CT, surgically created anatomical structures are represented as morphological abnormalities:

• There are two sub-hierarchies with concepts representing this type of content: 245849007 | Post-surgical anatomy (morphologic abnormality) and 43526002 | Operative site (morphologic abnormality).

• For example 245857005 | Stoma (morphologic abnormality) and its subtypes are used to model the FINDING SITE and DIRECT MORPHOLOGY for clinical finding and procedures concepts respectively.

Based on existing guidance, "Presence of <surgically created anatomical structure>" would expect to be represented as situation with explicit context concepts.  However, this content is also located within the clinical finding hierarchy. As shown in the table below, there are several existing concepts of this nature. In addition, there are several requests in SIRS for this type of concept and all have been requested as clinical findings.  (Please see Appendix A for SIRS requests and Appendix C for a list of existing concepts.) The current situation with explicit context concept model does not allow <body structure> concepts as values for the ASSOCIATED FINDING attribute. Therefore, like the pattern "Presence of <device>," this content also presents significant modelling challenges, and recommendations will be addressed in Section 6 of this document.

Laboratory finding contents

Existing subtypes of 441742003 | Evaluation finding (finding) include over 200 concepts following the patterns "Presence of X" and "X present." Although there are instances of something normally present e.g., 250441008 | Epithelial cells present (finding), this is not always the case e.g., 250439007 | Pus cells present (finding). Some laboratory findings are expressed in the format we would expect of an observable entity concept e.g. 365707003 | Finding of presence of viral antigen (finding).  These are grouper concepts and although some have subtypes of "X present (finding)"; others have no subtypes so do not appear to stand on their own merit as findings.  In the example given, the concept is modelled with the attribute INTERPRETS with the value 122433001 | Viral antigen assay (procedure).  Concepts following the pattern, "Finding of presence of X," without subtypes seem ambiguous.  Some of this content originates from United Kingdom National Health Service (UK NHS) Read codes, but within the Read codes, the map from X76zR | Presence of viral antigen (this is a synonym of 365707003 | Finding of presence of viral antigen (finding)) is to 122433001 | Viral antigen assay (procedure), supporting the suggestion that the concept is redundant and ambiguous.
Laboratory finding content was an exception to the working modelling approach and some content representing abnormal test results was historically added to the clinical finding hierarchy. However, in 2013, the IHTSDO entered a cooperative agreement with the Regenstrief Institute, the owners of the Logical Observation Identifiers Names and Codes (LOINC) standardized terminology. As part of this agreement, the addition of new pre-coordinated laboratory content will be significantly restricted within SNOMED CT. Existing content is now being addressed as part of artf6144 : Evaluation findings, evaluation procedures and artf6283 : Observables and investigation procedures redesign. For these reasons, the domain of laboratory content will be considered out of scope for the purposes of this project.

Absence of X / X absent / X not present content