This wiki has undergone a migration to Confluence found Here

Allergies and Adverse Reactions

From HL7Wiki
Jump to navigation Jump to search

Both SNOMED CT and HL7 differentiate an isolated reaction event from the condition of being allergic or intolerant. For instance, the following hierarchy is present in SNOMED CT (Jan 2007 release):

  • [ 404684003 | Clinical finding ]
    • [ 420134006 | Propensity to adverse reactions ]
      • [ 106190000 | Allergy ]
        • [ 416098002 | Drug allergy ]
    • [ 281647001 | Adverse reaction ]
      • [ 416093006 | Allergic reaction to drug ]

Different SNOMED CT value sets may apply, depending on the application context. Potential value sets include:

  • Substance/Product value set: [[[11]]] Values drawn from [ 105590001 | Substance ] and/or [ 373873005 | Pharmaceutical / Biologic product ] hierarchies, might be used where the context is the recording of substances to which the patient is allergic (e.g. a data entry box labeled "ALLERGIES"). [[[12]]]
  • Findings value set: Values drawn from [ 413350009 | Finding with explicit context ] and/or [ 404684003 | Clinical finding ] hierarchies, might be used where the context is an encounter diagnosis or a problem list.

NOTE: The HL7 Patient Care Technical Committee is developing a formal model for allergy tracking, which supports the representation of the sequential determination of primary and secondary observations relating to discovery and analysis of adverse reactions. The examples provided here are greatly simplified so as to illustrate certain aspects of SNOMED CT implementation.

<observation classCode="OBS" moodCode="EVN">
  <code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
  <text>Allergy to PCN manifesting as hives</text>
  <value xsi:type="CD" code="106190000|Allergy|:246075003|Causitive agent|=373270004|Penicillin - class of antibiotic - (substance)" codeSystem="2.16.840.1.113883.6.96"/>
  <actRelationship typeCode="MFST" inversionInd="true" contextConductionInd="true">
    <observation classCode="OBS" moodCode="EVN">
      <code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
      <value xsi:type="CD" code="247472004|Hives|" codeSystem="2.16.840.1.113883.6.96">
        <displayName value="Hives"/>

Where the clinician fills in both the substance/product and the reaction, context can propagate across the MFST relationship. The manifestation should not be post-coordinated with the allergic disorder (i.e. this guide recommends against a single post-coordinated expression such as "penicillin allergy manifesting as hives").

<observation classCode="OBS" moodCode="EVN">
  <code code="ASSERTION" codeSystem="2.16.840.1.113883.5.4"/>
  <value xsi:type="CD" code="91936005|Allergy to penicillin|" codeSystem="2.16.840.1.113883.6.96">
    <displayName value="Allergy to penicillin"/>
  <text>Allergy to PCN</text>

In this case, the selected finding indicates the condition of being allergic.