Description

Find classes with drug members similar to the list specified by the rxcuis.

The scoreType parameter selects the kind of similarity to find:

Equivalance

The class indicated by parameters has the same membership as the result class. Classes scoring lower than equivalenceThreshold are not returned.

Includes

The class indicated by parameters includes the result class. That is, the resulting drug classes have a large number of members which are included in the input drug class. This would be any resulting drug classes which have an inclusion score greater than 0. A minimum inclusion score can be set with the inclusionThreshold parameter.

Included-in

The class indicated by parameters is included in the ideal result class. That is, the class indicated by parameters has a large number of members contained in the returned drug classes. This would be any resulting drug classes which have an inclusion score less than 0. Minimum inclusion quality can be set with the inclusionThreshold parameter.

The results may be limited to classes of a specified source (relaSource parameter) and relationship (rela parameter). See getClassMembers for a table of useful source and relationship combinations.

Class similarity compares clinically-significant RxNorm ingredients, which may be different from the drugs reported by getClassMembers. See Similarity Scoring for details on how the similar classes are determined.

The classes' similarity scores are returned in response elements equivalenceScore and inclusionScore. A summary of the basis of computation is returned in intersection, cardinality1, and cardinality2. More detail about the basis of computation of the scores is available from getSimilarityInformation.

Parameters

All query parameters are case-insensitive.

Note that HTTP requires that query parameters be "URL encoded". For instance, a "space-separated list" will, in practice, usually appear to use either a plus sign (+) or %20 as the separator. For full information on URL encoding, please refer to IETF RFC 3986, "Uniform Resource Identifier".

Output structure

Results are available as either XML or JSON.

• The XML result has the root element rxclassdata. It is described in the XML Schema for the RxClass API; the relevant element structure is summarized below. Elements that would be empty might be left out.

• The JSON result is an object {...}, analogous to the content of the XML rxclassdata. Fields that might occur multiple times in the XML are expressed as an array. Fields that would be empty might be null or left out. Numbers are expressed as strings.

Both XML and JSON results follow the same outline:

rxclassdata

Root element in XML, or anonymous object in JSON

similarityMember

ingredientRxcui (array)

RxNorm identifier of an ingredient

rankClassConcept (array)

Drug class and its similarity stats

similarityEntityItem

Similarity stats

equivalenceScore

Degree of overlap of two classes

inclusionScore

Degree to which one compared class includes the other

intersection

Number of drugs common to both classes

cardinality1

Number of drugs in class 1

cardinality2

Number of drugs in class 2

drugClassConceptItem

Compared class

rela

Member relationship that defines the class

relaSource

Drug-member relationship source

rxclassMinConceptItem

Drug class

classId

Class identifier (an ID in the namespace of the class source)

className

Class name

classType

Class type (ATC1-4, CHEM, DISPOS, EPC, VA, etc.)

classUrl

Link to the class source

See also

• findSimilarClassesByClass

• getSimilarityInformation

Example: Classes with membership most similar to: morphine (id=7052), opium (RxCUI 7676), oxycodone (RxCUI 7804) and dihydrocodeine (RxCUI 23088)

XML: https://rxnav.nlm.nih.gov/REST/rxclass/class/similarByRxcuis?rxcuis=7052+7676+7804+23088&top=3

JSON: https://rxnav.nlm.nih.gov/REST/rxclass/class/similarByRxcuis.json?rxcuis=7052+7676+7804+23088&top=3

An XML result is shown below.

<rxclassdata>
    <similarityMember>
        <ingredientRxcui>23088</ingredientRxcui>
        <ingredientRxcui>7052</ingredientRxcui>
        <ingredientRxcui>7676</ingredientRxcui>
        <ingredientRxcui>7804</ingredientRxcui>
        <rankClassConcept>
            <similarityEntityItem>
                <equivalenceScore>0.5962848</equivalenceScore>
                <inclusionScore>-1.0</inclusionScore>
                <intersection>4</intersection>
                <cardinality1>4</cardinality1>
                <cardinality2>6</cardinality2>
            </similarityEntityItem>
            <drugClassConceptItem>
                <rela/>
                <relaSource>ATC</relaSource>
                <rxclassMinConceptItem>
                    <classId>N02AA</classId>
                    <className>Natural opium alkaloids</className>
                    <classType>ATC1-4</classType>
                </rxclassMinConceptItem>
            </drugClassConceptItem>
        </rankClassConcept>
        <rankClassConcept>
            <similarityEntityItem>
                <equivalenceScore>0.3211308</equivalenceScore>
                <inclusionScore>-0.45</inclusionScore>
                <intersection>3</intersection>
                <cardinality1>4</cardinality1>
                <cardinality2>7</cardinality2>
            </similarityEntityItem>
            <drugClassConceptItem>
                <rela>has_ingredient</rela>
                <relaSource>MEDRT</relaSource>
                <rxclassMinConceptItem>
                    <classId>D009022</classId>
                    <className>Morphine Derivatives</className>
                    <classType>CHEM</classType>
                </rxclassMinConceptItem>
            </drugClassConceptItem>
        </rankClassConcept>
        ...
    </similarityMember>
</rxclassdata>