SNOMED CT® Release Format 1 (RF1) Guide - ihtsdo

As a result of this limitation some currently released fully defined concept definitions may include conditions
that are necessarily true but are not required as part of the set of sufficient conditions.
Example: Consider the two definitions shown below:
116680003 | is a |=64572001 | disease | , 246075003 | Causative agent |=113858008 | mycobacterium
tuberculosis complex | { 116676008 | associated morphology |=6266001 | granulomatous inflammation
| , 363698007 | finding site |=39352004 | joint structure |}
Figure 15: | tuberculous arthritis |
116680003 | is a |=64572001 | disease | , 246075003 | causative agent |=41146007 | bacteria | {
116676008 | associated morphology |=23583003 | inflammation |, 363698007 | finding site |=39352004
| joint structure |}
Figure 16: | bacterial arthritis |
The definition of | tuberculous arthritis | differs from that of | bacterial arthritis | in two respects. In practice
the first of these ( | causative agent |= | mycobacterium tuberculosis complex |) is sufficient to define the
concept. However, the nature of the inflammation that results is, necessarily, granulomatous.
Thus an expression that specifies | bacterial arthritis | with | causative agent |=| mycobacterium
tuberculosis complex | is clinically equivalent to the concept | tuberculous arthritis | even though it does
not explicitly refine the nature of the inflammation.
In contrast the current SNOMED CT model computes | bacterial arthritis | with | causative agent |=|
mycobacterium tuberculosis complex | as supertype of | tuberculous arthritis |. This occurs because the
expression | bacterial arthritis | with | causative agent |=| mycobacterium tuberculosis complex | does
not specify of the nature of the inflammation.
Future enhancements: Options for distinguishing the sufficient set of defining relationships from those
that are merely necessarily true are being investigated. A complete solution to this issue needs to support
the recognition of several separate sufficient sets. However, initially a solution recognizing a single
sufficient set may be introduced.
2.2.1.3.3.4. Impact on retrieval
A necessary definition is inevitably more complete than a sufficientdefinition. From the perspective of retrieval
the completeness of a definition is a mixed blessing.
• It is an advantage for candidate expressions as they will be subsumed by a wider set of appropriate
predicates.
• It is a disadvantage for a predicate expression, the necessary conditions may result in incomplete retrieval.
A candidate expression that satisfies all the sufficient conditions should be included. However, it will be
excluded unless it satisfies all the necessary conditions in the predicate.
This occurs where the definition of a concept states conditions that are necessarily true but which go beyond
those that are sufficient to distinguish a concept from its supertypes.
Example:
The normal form definition of | pulmonary tuberculosis | is as follows:
116680003 | is a | = 64572001 | disease |
,246075003 | causative agent | = 113858008 | mycobacterium tuberculosis complex |
{116676008 | associated morphology | = 6266001 | granulomatous inflammation |
,363698007 | finding site | = 39607008 | lung structure | }
Used as a query predicate, this will exclude valid candidate expressions such as ...
Structure and Content Guide | 43
233604007 | pneumonia | : 246075003 | causative agent | = 113861009 | mycobacterium tuberculosis |
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