Project Initiation and Scoped Hierarchies

It was noted that the initial scope for this project was defined by the Member Forum, who requested focused review of several high-priority mental health disorder hierarchies due to known quality and consistency concerns. The hierarchies identified for initial review were:

• 13746004 |Bipolar disorder (disorder)| = 112 concepts

• 35489007 |Depressive disorder (disorder)| = 142 concepts

• 58214004 |Schizophrenia (disorder)| = 47 concepts

• 33449004 |Personality disorder (disorder)| = 48 concepts

• 110359009 |Intellectual disability (disorder)| = 556

Summary of Issues Raised by Member Forum

• Missing or outdated concepts.

• Legacy content derived from multiple classification systems (ICD-9, ICD-10, ICD-11; DSM-III, DSM-IV, DSM-5), resulting in mixed patterns within hierarchies.

• Incorrect terms, for example 371599001 |Severe bipolar I disorder (disorder)|, where severity should instead be represented at the episode level rather than as an inherent characteristic of the disorder.

• Presentation from Norway highlighting some of the challenges faced.

The Mental Health Disorders Project Group was subsequently convened to deliver the work, with members nominated by National Release Centres or recruited via an open expression of interest.

Requested Areas of Review

The Member Forum asked that the hierarchies listed above be reviewed and refined with the following objectives:

1. Improve descriptions and synonyms in line with current SNOMED CT policy.

2. Identify and resolve ambiguous, duplicate, outdated, or potentially stigmatising concepts.

3. Content originating from older classification systems may remain where clinically acceptable and non-offensive.

4. Review and correct hierarchical placement ensuring clinically appropriate parent-child relationships.

Project meeting participants raised several general observations during discussion, including:

• Several Members reported difficulty locating appropriate content for recording clinical detail, indicating perceived limitations in the current level of expressivity within the mental health disorder hierarchies.

• A question was raised regarding the balance between pre-coordination and post-coordination, with concern expressed that current systems — and potentially SNOMED CT itself — may not consistently support complex post-coordination for mental health concepts in practice.

• Members noted that while SNOMED CT provides the foundational terminology and availability of concepts, effective use in practice also depends on national and local implementation guidance, including usage policies, reference sets, and tooling support.

Implications for the project

It was noted that the observations raised by participants reinforce the need for the Project Group to:

• Consider expressivity and discoverability when reviewing and refining disorder hierarchies.

• Evaluate the appropriate balance between pre-coordination and post-coordination considering real-world system capabilities and implementation environments.

• Ensure that any significant modelling changes are accompanied by clear documentation explaining their intended clinical use and implementation; and

• Identify where terminology changes alone may be insufficient, and where international, national or local implementation guidance may be required to support consistent adoption.

These considerations will inform prioritisation decisions, risk assessment, and the approach to consultation with Members and CRGs as the project progresses.

Follow-Up Actions

• Circulate the initial scope, rationale, and project process to all Project Group members.

• Issue a survey to Project Group members to collect examples and use cases relating to the scoped hierarchies, and to invite identification of any additional priority issues for consideration.

• Assess the feasibility of using the University of Michigan clinical consensus tool to support structured expert input and decision-making.