Implementation guide for digital medicines

3. Periods of no medicine administration

As part of a MedicationRequest

There is no clear way in the R4 Dosage structure to define a period of no medicine administration within a MedicationRequest resource.

The example given above for Colchicine tablets also includes an instruction for a period of time where medication should not be taken;

Do not repeat course for 3 days

Another clinical example would be for a Lidocaine medicated plaster. A typical written dosage instruction would be;

Apply 2 patches once daily to the affected area for up to 12 hours, followed by a 12-hour plaster-free period; to be applied to intact, dry, non-hairy, non-irritated skin.

The R4 Dosage structure cannot describe, in a machine readable way, the clauses "Do not repeat course for 3 days" and “followed by a 12-hour plaster-free period”.

As part of a MedicationAdministration or MedicationStatement

Within medicine administration records it is important, for certain medication, to clearly state periods where no medication was administered.

Two approaches are possible within the FHIR standard.

The first is to infer periods of no administration where there are no MedicationAdministration or MedicationStatement records that cover a given period of time. This approach is not recommended as not all records will be defined using an effectivePeriod.start and effectivePeriod.end date/time range. Some records will just be recorded with an effectiveDateTime. Depending on how specific the dosage instruction has been defined, the expected administration period could be calculated. However this approach is based on assumptions, not facts.

The second, and preferred solution, is to record a zero quantity and a status of "on-hold" within a MedicationAdministration or MedicationStatement record for a medicine for a specific effectivePeriod. This example is an administration record of a 1-hour pause during a Heperain infusion. The rateQuantity is "0" (zero). The status is "on-hold".

<MedicationAdministration xmlns="http://hl7.org/fhir">
    <id value="f8fced11-53c3-47c3-92a8-ff49dc1b0e0b" />
    <meta>
        <profile value="https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationAdministration" />
    </meta>
    <status value="on-hold" />
    <medicationCodeableConcept>
        <coding>
            <system value="https://dmd.nhs.uk" />
            <code value="36054511000001107" />
            <display value="Heparin sodium 20,000units/20ml solution for injection ampoules" />
        </coding>
    </medicationCodeableConcept>
    <subject>
        <reference value="Patient/UKCore-Patient-RachelSmith-Example" />
    </subject>
    <effectivePeriod>
        <start value="2021-03-26T16:30:00+00:00" />
        <end value="2021-03-26T17:30:00+00:00" />
    </effectivePeriod>
    <request>
        <reference value="MedicationRequest/203c8dce-aaec-4349-9335-a572ad48c553" />
    </request>
    <dosage>
        <route>
            <coding>
                <system value="https://dmd.nhs.uk" />
                <code value="47625008" />
                <display value="Intravenous" />
            </coding>
        </route>
        <method>
            <coding>
                <system value="http://snomed.info/sct" />
                <code value="261754007" />
                <display value="Continuous infusion" />
            </coding>
        </method>
        <rateQuantity>
            <value value="0" />
            <unit value="millilitre per hour" />
            <system value="http://unitsofmeasure.org" />
            <code value="mL/h" />
        </rateQuantity>
    </dosage>
</MedicationAdministration>

{
    "resourceType": "MedicationAdministration",
    "id": "f8fced11-53c3-47c3-92a8-ff49dc1b0e0b",
    "meta": {
        "profile":  [
            "https://fhir.hl7.org.uk/StructureDefinition/UKCore-MedicationAdministration"
        ]
    },
    "status": "on-hold",
    "medicationCodeableConcept": {
        "coding":  [
            {
                "system": "https://dmd.nhs.uk",
                "code": "36054511000001107",
                "display": "Heparin sodium 20,000units/20ml solution for injection ampoules"
            }
        ]
    },
    "subject": {
        "reference": "Patient/UKCore-Patient-RachelSmith-Example"
    },
    "effectivePeriod": {
        "start": "2021-03-26T16:30:00+00:00",
        "end": "2021-03-26T17:30:00+00:00"
    },
    "request": {
        "reference": "MedicationRequest/203c8dce-aaec-4349-9335-a572ad48c553"
    },
    "dosage": {
        "method": {
            "coding":  [
                {
                    "system": "http://snomed.info/sct",
                    "code": "261754007",
                    "display": "Continuous infusion"
                }
            ]
        },
        "route": {
            "coding":  [
                {
                    "system": "https://dmd.nhs.uk",
                    "code": "47625008",
                    "display": "Intravenous"
                }
            ]
        },
        "rateQuantity": {
            "value": 0,
            "unit": "millilitre per hour",
            "system": "http://unitsofmeasure.org",
            "code": "mL/h"
        }
    }
}