Observation Qualification Using ActRelationships
Constrained information models specified by some Domain committees use an ActRelationship to allow one Observation to qualify the meaning of another Observation. For example, to specify the severity of an abnormal observation.
SNOMED CT includes qualifiers that allow refinement of meaning using post-coordinated expressions. As a result, the use of an additional Observation class is unnecessary and introduces alternative ways to represent the same meaning.
The following rules are specified to simplify interpretation by minimizing unnecessary variability in representation.
- A constrained information model or template that permits use of SNOMED CT as one of the permitted ways to represent the result of an Observation, MAY include related Observation classes included to permit qualification of the meaning of an Observation but inclusion of these qualifying class SHALL NOT be required.
- A constrained information model or template that requires use of SNOMED CT to represent the result of an Observation SHALL NOT include any related Observation classes included to permit qualification of the meaning of an Observation.
- An Observation class instance in which the Observation.value is represented by a SNOMED CT expression SHALL NOT include any related qualifying classes but SHOULD encode the relevant qualifications as part of the expression.
It is important to reduce the scope for unnecessary alternative representation of the same information. Tight coupling of the qualification to the primary result of the observation is likely to reduce the risk of misinterpretation.