Implementation guide for interoperable medicines

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

Element: method

Note: Guidance on method under review to consider including use cases for when a free-text method instruction may be required.

The 999000041000001103 ePrescribing method simple reference set (foundation metadata concept) reference set collates the commonly used terms for method for use in the United Kingdom. Additional terms can be requested to be added to this reference set.

For example:

<!-- Method, using a preferred term -->
<method>
    <coding>
        <system value="http://snomed.info/sct"/>
        <code value="71791000001107"/>
        <display value="Nebulise - method of drug administration (qualifier value)"/>
    </coding>
</method>

and

<!-- Method, using a synonym -->
<method>
    <coding>
        <extension url="https://fhir.hl7.org.uk/StructureDefinition/Extension-UKCore-CodingSCTDescDisplay">
            <valueString value="Injection" />
        </extension>
        <system value="http://snomed.info/sct"/>
        <code value="129326001"/>
        <display value="Injection - action"/>
    </coding>
</method>

Whilst a FHIR value-set for method does exist, together with two separate hierarchies within SNOMED-CT (Dose form administration method and Dosing instruction fragment), it is recommended to use the ePrescribing reference set in the first instance.

Use of a free-text method

The method element with the Dosage structure can be populated with a free-text instruction. However, where a suitable coded SNOMED term exists, the coded term should always be used to allow the instruction to be machine-readable.

Scenarios exist where a suitable coded SNOMED term for method does not exist. For example, some paediatric-suitable methods of medication administration and where complex methods are required.

Example: Nystatin 100,000units/ml oral suspension sugar free for paediatric use.

<method>
   <text value="Rub onto the inside of the mouth and gums"/>
</method>

Example: Tiotropium bromide 18microgram inhalation powder capsules with device

<method>
   <text value="Inhale the contents"/>
</method>

Example: Creon capsules

<method>
   <text value="Swallowed whole or for ease of administration may be opened and the granules taken with acidic fluid or soft food but without chewing"/>
</method>

Considerations when mapping legacy dosage instructions to FHIR Dosage

Where an implementation approach is based on mapping of legacy text-based dosage instructions to the FHIR Dosage structure, the method described in text may not a like-for-like match a coded SNOMED method. In some cases there will be a suitable SNOMED coded term so we recommend involving clinicians during any mapping exercise.

For example. Some historic mouthwash medication records may use the text-based method within the dosage of "Rinse or Gargle". There is a coded SNOMED term of "Use as a mouthwash" (93481000001108) which could be more suitable.

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