Dose syntax implementation guidance for FHIR STU3

This guidance is under active development by NHS Digital and content may be added or updated on a regular basis.

3. STU3 Limitation - Cyclical prescribing - Defining a period of time where medication should not be taken

Workaround: Use a free-text `Dosage.additionalInstruction`.

The example given for the current limitation for defining a maximum dose per course also includes an instruction for a period of time where medication should not be taken. This is not directly supported within the STU3 Dosage structure.

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 FHIR STU3 Dosage structure can describe all the above except for the clause “followed by a 12-hour plaster-free period”.

In a dose-based instruction this would needs to be expressed as free-text within a Dosage.additionalInstruction.

An example of a sequencial instruction can be found below.

Microgynon 30 tablets (Bayer Plc), 1 tablet, ONCE a DAY, oral, for 21 days, subsequent courses repeated after 7-day tablet-free interval

Product-based AMP prescription using additional instructions to convery pill free interval.
<MedicationRequest xmlns="http://hl7.org/fhir">
<id value="d4b05cfb-d444-4490-824a-67c55596c610" />
<contained>
<Medication>
<id value="med1" />
<code>
<coding>
<system value="http://snomed.info/sct" />
<code value="42111000001107" />
<display value="Microgynon 30 tablets (Bayer Plc)" />
</coding>
</code>
</Medication>
</contained>
<status value="active" />
<intent value="order" />
<medicationReference>
<reference value="#med1" />
</medicationReference>
<subject>
<identifier>
<system value="https://fhir.nhs.uk/Id/nhs-number" />
<value value="9999999999" />
</identifier>
</subject>
<dosageInstruction>
<additionalInstruction>
<text value="subsequent courses repeated after 7-day tablet-free interval" />
</additionalInstruction>
<timing>
<repeat>
<boundsDuration>
<value value="21" />
<unit value="day" />
<system value="http://unitsofmeasure.org" />
<code value="d" />
</boundsDuration>
<frequency value="1" />
<period value="1" />
<periodUnit value="d" />
</repeat>
</timing>
<route>
<coding>
<system value="http://snomed.info/sct" />
<code value="26643006" />
<display value="oral" />
</coding>
</route>
<doseQuantity>
<value value="1" />
<unit value="tablet" />
<system value="http://snomed.info/sct" />
<code value="428673006" />
</doseQuantity>
</dosageInstruction>
</MedicationRequest>
{
"resourceType": "MedicationRequest",
"id": "d4b05cfb-d444-4490-824a-67c55596c610",
"contained": [
{
"resourceType": "Medication",
"id": "med1",
"code": {
"coding": [
{
"system": "http://snomed.info/sct",
"code": "42111000001107",
"display": "Microgynon 30 tablets (Bayer Plc)"
}
]
}
}
],
"status": "active",
"intent": "order",
"medicationReference": {
"reference": "#med1"
},
"subject": {
"identifier": {
"system": "https://fhir.nhs.uk/Id/nhs-number",
"value": "9999999999"
}
},
"dosageInstruction": [
{
"additionalInstruction": [
{
"text": "subsequent courses repeated after 7-day tablet-free interval"
}
],
"timing": {
"repeat": {
"boundsDuration": {
"value": 21,
"unit": "day",
"system": "http://unitsofmeasure.org",
"code": "d"
},
"frequency": 1,
"period": 1,
"periodUnit": "d"
}
},
"route": {
"coding": [
{
"system": "http://snomed.info/sct",
"code": "26643006",
"display": "oral"
}
]
},
"doseQuantity": {
"value": 1,
"unit": "tablet",
"system": "http://snomed.info/sct",
"code": "428673006"
}
}
]
}
MedicationRequest.id[0]d4b05cfb-d444-4490-824a-67c55596c610
MedicationRequest.contained[0].id[0]med1
MedicationRequest.contained[0].code[0].coding[0].system[0]http://snomed.info/sct
MedicationRequest.contained[0].code[0].coding[0].code[0]42111000001107
MedicationRequest.contained[0].code[0].coding[0].display[0]Microgynon 30 tablets (Bayer Plc)
MedicationRequest.status[0]active
MedicationRequest.intent[0]order
MedicationRequest.medication[0].reference[0]#med1
MedicationRequest.subject[0].identifier[0].system[0]https://fhir.nhs.uk/Id/nhs-number
MedicationRequest.subject[0].identifier[0].value[0]9999999999
MedicationRequest.dosageInstruction[0].additionalInstruction[0].text[0]subsequent courses repeated after 7-day tablet-free interval
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].value[0]21
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].unit[0]day
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].system[0]http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].bounds[0].code[0]d
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequency[0]1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]d
MedicationRequest.dosageInstruction[0].route[0].coding[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].route[0].coding[0].code[0]26643006
MedicationRequest.dosageInstruction[0].route[0].coding[0].display[0]oral
MedicationRequest.dosageInstruction[0].dose[0].value[0]1
MedicationRequest.dosageInstruction[0].dose[0].unit[0]tablet
MedicationRequest.dosageInstruction[0].dose[0].system[0]http://snomed.info/sct
MedicationRequest.dosageInstruction[0].dose[0].code[0]428673006
MedicationRequest
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