Following review and agreement within the Nutrition & Dietetics Clinical Reference Group, this briefing note informs the SNOMED community of planned modelling updates to concepts relating to obesity and central obesity. The changes address identified clinical inaccuracies and align SNOMED CT with internationally accepted definitions and usage.
| Date created | 26 February 2026 |
|---|---|
| Action | For Information Only |
| Status | Open |
Changes to Obesity and Central Obsesity.pdf (142.1 KB)
I appreciate this note is offered ‘for information’, however I have a few questions:
a. If (i) “…Obesity is diagnosed on the basis of excess adiposity…” and (ii) SI are a long way through consulting on a novel mechanism that will support “…modelling physiological state disorders representing excesses of substance or cell types…”, what is the reason for not using this new mechanism to model ‘obesity’ (if seen as an ‘excess’ in number and size of fat cells)?
b. leaving aside a long-standing and more general concern regarding the interprets/has_interpretation modelling pattern, why are SI recommending the use of property-less observables as the targets for the ‘interprets’ aspect of the proposed solution? The suggested ‘Interprets = Body fat’ component is silent on what ‘property’ of the body fat is determined to be ‘excessive’? ‘Interprets = Distribution of body fat’ does offer the word ‘distribution’ as a possible property, but it is not clear what values such a property should take and whether ‘excessive’ is therefore a valid value.
c. Will any of the concepts discussed be published as sufficiently defined? The query…
<< 404684003 | Clinical finding |: {363714003 | Interprets | = << 248300009 | Body fat observable |, 363713009 | Has interpretation | = << 260378005 | Excessive |}
…returns a small number of released concepts, notably 248302001 |Excess subcutaneous fat| and its descendants. Would SI now expect these to classify as kinds of 414915002 |Obese (finding)|, and if so is this the intended outcome?
Thank you Ed for taking the time to read the briefing note and for raising these questions.
The note’s purpose is to address a specific, clinically identified inaccuracy in released content — namely, the modelling of obesity in terms of body weight rather than excess adiposity — rather than to introduce or pilot new or emerging modelling mechanisms.
With respect to (a), consultation on the excess mechanism has recently closed without additional comments. However, implementation will take time because new attributes must be defined and incorporated into the MRCM. For clinical findings, the proposed HAS EXCESS OF attribute is not appropriate, as its domain is << Disease, and clinical findings instead use the INTERPRETS / HAS INTERPRETATION role group.
Given this, and the need to resolve known clinical issues in the current release, the agreed approach was to use established modelling patterns that reflect how obesity is diagnosed and recorded in clinical practice.
Regarding (b), the use of observables such as Body fat with Has interpretation = Excessive is intentional and consistent with existing SNOMED CT usage. This reflects a clinical assessment that adiposity, or its distribution, is excessive, without asserting a specific measurement method or property. In practice, diagnosis commonly relies on proxy measures (e.g. BMI or waist–hip ratio) and may also be informed by measurements of fat mass, percentage, or volume. Clinicians interpret all these measures rather than treating them as defining characteristics, pending wider adoption of more direct body composition methods (such as DXA). Though obesity is likely to remain a phenotypic, interpretation-based condition, potentially informed by those measurements but not reducible to them.
On (c), there is no intention at this stage to sufficiently define 414915002 |Obese (finding)|. Retaining a primitive definition avoids unintended subsumption of more specific fat findings (e.g. excess subcutaneous fat) under obesity, which would not be clinically appropriate. The proposed changes are therefore necessary to improve accuracy, but not sufficient to support full logical definition without risking misclassification.
I hope this clarifies the intent and scope of the proposed updates.