![]() A second tree walk then allocates one or more branch number ranges to each concept, which contains the number of all of their descendants. In this approach, a depth first tree walk is performed that applies an incremental number to each concept. In this approach, a database is used which supports the recursive testing of a chain of hierarchical relationships. This reduces the number of tests that need to be performed to recursively test the subtype relationships. A concept can only subsume concepts that include the same set of high-level concept flags. In this approach, flags are added to each concept to indicate the set of high-level concept nodes of which that concept is a subtype. Semantic type identifiers and hierarchy flags.In this approach, every possible sequence of |is a | relationships are recursively tested from the candidate concept until the predicate concept is reached or until all possible paths have been exhausted. Exhaustive testing of subtype relationships.Approaches for testing subsumption between precoordinated concepts include: When the candidate and predicate expressions are both precoordinated concepts, subsumption testing can use the published relationships from the SNOMED CT release files. A variety of approaches exist for testing subsumption. Rapid and efficient computation of whether a concept |is a | subtype descendant of another concept is essential for testing subsumption between expressions. Implementation Testing Subsumption Between Concepts Note that patient 456872 would not be returned by this query as neither 22298006 |myocardial infarction | or 195967001 |asthma | are subtypes of 40733004 |infectious disease |. 634711 (because 415353009 |rotavirus food poisoning | is a subtype of 40733004 |infectious disease |). ![]() Then this query would return the following list of patients: If the health records contained the following data: WHERE diagnosis = (<< 40733004 |infectious disease |) In this scenario, the following simple query could be executed to find all the patients whose health record contains a diagnosis that is subsumed by the concept 40733004 |infectious disease |: ExampleĪ typical example using subsumption would be an audit within a hospital, reviewing all patients with an infectious disease. These are summarized in the Implementation sub-section below. There are a variety of ways to implement subsumption testing. Is satisfied by any expression that is subsumed by 40733004 |infectious disease |. ![]() Subsumption testing can be represented using the SNOMED CT Expression Constraint Language using the '<' (descendantOf) or '<<' (descendantOrSelfOf) operators. In this case, the candidate expression is subsumed by the predicate expression. For example:Ĭandidate expression: 75570004 |viral pneumonia | Subsumption testing between expressions tests to see if the candidate expression (often recorded in a patient record) is subsumed by a predicate expression (typically part of the query being run across the patient record). For example, 75570004 |viral pneumonia | is a 40733004 |infectious disease | and therefore 40733004 |infectious disease | subsumes 75570004 |viral pneumonia |, and 75570004 |viral pneumonia | is subsumed by 40733004 |infectious disease |. Subsumption testing between concepts is represented using a stated or implied |is a | relationship. ![]() If clinical meaning X is a subtype of clinical meaning Y, then Y is said to 'subsume' X and X is 'subsumed by' Y. ![]() Subsumption occurs when one clinical meaning is a subtype of another clinical meaning, and testing for this is called 'subsumption testing'. For example, answering the question 'Which patients have an infectious disease?' involves finding all the patients with any kind of infectious disease (e.g. Determining whether one concept (or expression) is a kind of another concept (or expression) is the fundamental capability enabled by SNOMED CT. ![]()
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