Medications and Immunizations

3.6

Areas of overlap between HL7 and SNOMED CT include the source of information, as described above (see 3.1.3 Source of information). This is particularly important for medications, where one needs to differentiate what a patient is actually having administered vs. what is being dispensed. The former is typically gleaned from the patient, family member, or the medication administration record for an inpatient. The latter is often gleaned from a pharmacy application.

Another area of overlap between HL7 and SNOMED CT includes the method and route by which a substance is administered. Various ways by which this information can be represented include:

• SNOMED CT defining attributes (whether pre- or post-coordinated)
  • [ 260686004 | Procedure method ]: Used to indicate the method by which a procedure is performed.
  • [ 410675002 | Route of administration ]: Used to indicate the route by which a substance is administered.
• RIM attributes
  • SubstanceAdministration.code: A code further describing the type of administration.
  • SubstanceAdministration.routeCode: The method of introducing the therapeutic material into or onto the subject.

The following patterns post-coordinate within SubstanceAdministration.code to represent the route of administration. Within a particular realm, or as required by a particular implementation, there may also be a need to populate SubstanceAdministration.routeCode, possibly with values drawn from a required and non-SNOMED CT value set.

The level of detail by which an administered substance is known can vary greatly, particularly when dealing with patient recollection.

SNOMED CT has both a [ 105590001 | Substance ] hierarchy and a [ 373873005 | Pharmaceutical / Biologic Product ] hierarchy, and may have realm-specific drug extensions that include manufacturer-specific product codes. Concepts from the Substance hierarchy SHOULD NOT be used to code an administered substance.

In the following examples, the pharmacy is dispensing atenolol 50mg tablets with instructions to take one tablet per day, whereas the patient's daughter says that only a half-tablet per day is being ingested.

3.6.1

<substanceAdministration classCode="SBADM" moodCode="INT">
  <code code="432102000|Administration of therapeutic substance|:410675002|Route of administration|=26643006|Oral route|" codeSystem="2.16.840.1.113883.6.96"/>
  <text>Atenolol 50mg tablet, take 1 per day</text>
  <effectiveTime xsi:type="PIVL_TS">
    <period value="24" unit="h"/>
  </effectiveTime>
  <doseQuantity value="1"/>
  <consumable typeCode="CSM">
    <manufacturedProduct classCode="MANU">
      <manufacturedLabeledDrug classCode="MMAT" determinerCode="KIND">
        <code code="318420003|Atenolol 50mg tablet|" codeSystem="2.16.840.1.113883.6.96">
          <displayName value="Atenolol 50mg tablet"/>
        </code>
      </manufacturedLabeledDrug>
    </manufacturedProduct>
  </consumable>
  <actRelationship typeCode="XCRPT" contextConductionInd="false">
    <actReference classCode="SBADM" moodCode="EVN">
      <id root="b3440e50-8f48-11da-a72b-0800200c9a66"/>
    </actReference>
  </actRelationship>
</substanceAdministration>

This act represents an excerpt from a pharmacy application.

3.6.2

<substanceAdministration classCode="SBADM" moodCode="EVN">
  <code code="432102000|Administration of therapeutic substance|:410675002|Route of administration|=26643006|Oral route|" codeSystem="2.16.840.1.113883.6.96"/>
  <text>Atenolol 50mg tablet, taking 1/2 per day</text>
  <effectiveTime xsi:type="PIVL_TS">
    <period value="24" unit="h"/>
  </effectiveTime>
  <doseQuantity value="0.5"/>
  <consumable typeCode="CSM">
    <manufacturedProduct classCode="MANU">
      <manufacturedLabeledDrug classCode="MMAT" determinerCode="KIND">
        <code code="318420003|Atenolol 50mg tablet|" codeSystem="2.16.840.1.113883.6.96">
          <displayName value="Atenolol 50mg tablet"/>
        </code>
      </manufacturedLabeledDrug>
    </manufacturedProduct>
  </consumable>
  <informant typeCode="INF">
    <relatedEntity classCode="PRS">
      <code code="66089001|Daughter|" codeSystem="2.16.840.1.113883.6.96">
        <displayName value="Daughter"/>
      </code>
    </relatedEntity>
  </informant>
</substanceAdministration>

This act represents information gleaned from the patient's daughter.