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.

2. STU3 Limitation - Defining a maximum dose per course

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

A maximum dose for three scenarios is supported within the STU3 Dosage structure;

  • maxDosePerPeriod - define a maximum dose over a given period of time
  • maxDosePerAdministration - defines a maximum dose per administration
  • maxDosePerLifetime - defines the maximum dose during the lifetime of the patient

Not currently supported is how to define a maximum dose per course.

With the current STU3 Dosage structure, a maximum dose per course would have to be conveyed in free-text using the Dosage.additionalInstruction.

<!-- Defining a maximum dose per course -->
<!-- Example: Colchicine 500microgram tablets, 500 micrograms, 2 to 4 times a day until symptoms relieved, maximum 6 mg per course, do not repeat course within 3 days -->
<MedicationRequest xmlns="http://hl7.org/fhir">
<id value="f27b260e-8bdf-11eb-8dcd-0242ac130003" />
<contained>
<Medication>
<id value="med1" />
<code>
<coding>
<system value="http://snomed.info/sct" />
<code value="330079002" />
<display value="Colchicine 500microgram tablets" />
</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="Maximum dose per course 6 mg" />
</additionalInstruction>
<additionalInstruction>
<text value="Do not repeat course for 3 days" />
</additionalInstruction>
<patientInstruction value="Until symptoms relieved" />
<timing>
<repeat>
<frequency value="2" />
<frequencyMax value="4" />
<period value="1" />
<periodUnit value="d" />
</repeat>
</timing>
<doseQuantity>
<value value="500" />
<unit value="microgram" />
<system value="http://unitsofmeasure.org" />
<code value="ug" />
</doseQuantity>
</dosageInstruction>
</MedicationRequest>
{
"resourceType": "MedicationRequest",
"id": "f27b260e-8bdf-11eb-8dcd-0242ac130003",
"contained": [
{
"resourceType": "Medication",
"id": "med1",
"code": {
"coding": [
{
"system": "http://snomed.info/sct",
"code": "330079002",
"display": "Colchicine 500microgram tablets"
}
]
}
}
],
"status": "active",
"intent": "order",
"medicationReference": {
"reference": "#med1"
},
"subject": {
"identifier": {
"system": "https://fhir.nhs.uk/Id/nhs-number",
"value": "9999999999"
}
},
"dosageInstruction": [
{
"additionalInstruction": [
{
"text": "Maximum dose per course 6 mg"
},
{
"text": "Do not repeat course for 3 days"
}
],
"patientInstruction": "Until symptoms relieved",
"timing": {
"repeat": {
"frequency": 2,
"frequencyMax": 4,
"period": 1,
"periodUnit": "d"
}
},
"doseQuantity": {
"value": 500,
"unit": "microgram",
"system": "http://unitsofmeasure.org",
"code": "ug"
}
}
]
}
MedicationRequest.id[0]f27b260e-8bdf-11eb-8dcd-0242ac130003
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]330079002
MedicationRequest.contained[0].code[0].coding[0].display[0]Colchicine 500microgram tablets
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]Maximum dose per course 6 mg
MedicationRequest.dosageInstruction[0].additionalInstruction[1].text[0]Do not repeat course for 3 days
MedicationRequest.dosageInstruction[0].patientInstruction[0]Until symptoms relieved
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequency[0]2
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].frequencyMax[0]4
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].period[0]1
MedicationRequest.dosageInstruction[0].timing[0].repeat[0].periodUnit[0]d
MedicationRequest.dosageInstruction[0].dose[0].value[0]500
MedicationRequest.dosageInstruction[0].dose[0].unit[0]microgram
MedicationRequest.dosageInstruction[0].dose[0].system[0]http://unitsofmeasure.org
MedicationRequest.dosageInstruction[0].dose[0].code[0]ug
MedicationRequest
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