HL7 Europe Medication Prescription and Dispense
1.0.0 - trial-use 150

HL7 Europe Medication Prescription and Dispense, published by HL7 Europe. This guide is not an authorized publication; it is the continuous build for version 1.0.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/hl7-eu/mpd-r5/ and changes regularly. See the Directory of published versions

## Implementation Considerations

### Prescription - document or request approach

Prescription has historically been a document that authorises one or multiple requests. In FHIR, there is no explicit resource for Prescription, and it is possible to focus on the document aspect or the request aspect. Some countries have preferred to keep the document view using Bundle with Composition. This IG does not encourage nor ban this approach, but there is no profile for document Bundle in the IG.

Examples in this IG use collection Bundle simply for making it easier to read for the humans. Many implementers use transaction Bundle for creating new prescriptions as it allows assigning server-side IDs more easily.

The choice of wrapping the request and its related resources in a Bundle or not, is entirely up to the implementers.

### Multi-item prescriptions

Systems are not required to support multi-item prescriptions in order to be compliant with this implementation guide.

The recommended way of designing prescriptions in HL7 FHIR is to have one item per prescription. This is reflected in the MedicationRequest resource where the Medication cardinality is 1..1. Currently, the European crossborder prescription CDA implementation also allows only one medication per prescription, expecting the country of origin to split a multi-item prescription into several crossborder prescriptions and track the dispensations accordingly. However, real life national prescription systems are often designed differently from this logic; in many countries a prescription may contain more than one medication item.

There is no single mechanism in HL7 FHIR for handling multi-item prescriptions. To choose the optimal solution, one must consider the business requirements and reasons behind a multi-item prescription:

- Is it used merely as a grouping mechanism without deeper semantics?
- Are there technical reasons why multiple items must be transported as one group?
- Are the items on prescription related to each other through the dosing scheme?
- Must the items be dispensed as one transaction?
- Are there pricing or reimbursement rules that are dependent on grouping?
- How does the status of a prescription relate to the statuses of individual requests?
- What are the consequences of adding or removing prescription items: can a single-item prescription become a multi-item prescription and vice versa?

Considering the requirements above, the best match from the following approaches can be chosen.

#### Option 1: No grouping

This option can only be used when the items on a prescription can be easily split and dispensed separately. The information about which prescription the items belong to is handled outside FHIR services.

Pros:

- Technically the easiest option to implement in FHIR.
- Allows the same handling of data for single- and multi-item prescriptions.

Cons:

- The prescription identifier is not present
- The complexity of matching the items and prescriptions does not disappear, but is pushed to the prescription/dispensing systems.
- Only applicable when individual items have no interdependencies.

#### Option 2: Using .groupIdentifier

This option differs from the previous one by one important aspect: the data element .groupIdentifier is filled with the prescription identifier. This allows linking different prescription items within FHIR services, but it does not provide any extra information about the prescription or interdependencies between different items on the same prescription. Systems that do not support multi-item prescriptions may ignore the groupIdentifier element and leave it unprocessed.

Pros:

- Easy to implement
- Allows very similar handling of data for single- and multi-item prescriptions
- .groupIdentifier preserves the prescription identifier.

Cons:

- No way to show interdependencies between individual items/requests
- The status of the prescription has to be the same or calculable from individual prescription items

#### Option 3: Using RequestOrchestration/RequestGroup

This option is technically more complex to handle on the FHIR side, but it allows communication of the interdependencies of different items on a prescription. Every prescription item uses the MedicationRequest resource just like in the first two options. However, an additional resource is populated to provide extra information about the semantics of grouping the items on the same prescription. RequestOrchestration (R5) or RequestGroup (R4) resource shares the same .groupIdentifier as the MedicationRequests that are linked to it. However, note that RequestOrchestration/RequestGroup is not semantically the prescription, but only a part of it. Even with this approach, there is no single resource for the prescription object as such. When exchanging this kind of prescription with another system, simplification may be needed: removing the RequestOrchestration/RequestGroup resource and exchanging individual MedicationRequests.

Pros:

- Possible to define interdependencies between prescription items.
- Multi-item prescription is clearly defined and distinguishable from single-item prescriptions.

Cons:

- Multiitem prescription and single-item prescription are handled differently. In a prescription system where multi-item prescriptions use RequestOrchestration/RequestGroup, it is important to consider whether single-item prescriptions should be using the same mechanism, even though it does not add anything to the semantics.
- Receiving systems outside the ecosystem are likely to drop the RequestOrchestration/RequestGroup resource when it's not explicitly supported in their implementation.

When grouping MedicationRequests with a RequestOrchestration/RequestGroup:

- MedicationRequest.intent value must be ‘option’. This is a signal to the receiver, that the request must be handled as part of a bigger request group.
- The element that binds MedicationRequest and RequestOrchestration/RequestGroup together is .groupIdentifier. By sharing the same .groupIdentifier value, they indicate that they are a part of the same prescription document.
- The prescription identifier should be the value of .groupIdentifier.
- MedicationRequests, if they originate from the same prescription, should have the same patient and authoring metadata.

The following diagram explains the process of splitting a custom multi-item prescription (yellow) into HL7 FHIR resources (green).

Please see examples 100A and 300A in the Artifacts page for more information about how to create a multi-item prescription using RequestOrchestration/RequestGroup, and example 200A for information about how to create a multi-item prescription without an additional grouping/organising resource. All examples in this IG use Bundle as a wrapper for multi-item prescription, however this is just for the convenience, and not a normative part of this IG. Implementers can choose whether to use Bundle or which type of Bundle to use.

Read more about using RequestOrchestration/RequestGroup in FHIR workflow pages.

### Prescription statuses and workflow

MedicationRequest has a very limited set of statuses available for use. This is a deliberate design choice to improve interoperability across different settings.

Prescription and dispensation systems often use additional or different statuses, and those statuses are not directly mappable to MedicationRequest.status. Some of these prescription statuses may actually be related to the dispense rather than the request, so the semantically correct place for some statuses would actually be MedicationDispense.status.

Some simple workflows may choose to make use of the .meta.tag 'actionable' to indicate whether the request is dispensable or simply for information. For more sophisticated workflows, especially when FHIR messaging is the basis of the workflow, Task resource should be used in addition to MedicationRequest and MedicationDispense. For group request, an additional RequestOrchestration/RequestGroup resource should be used.

Workflows are typically implementation-specific and the aim of this implementation guide is not to provide one solution for everyone. Practice of using prescription and dispensation statuses varies a lot across countries and use cases (e.g. hospital use vs community pharmacy). While it is important for each implementation to map their business statuses to FHIR MedicationRequest.status values, the usage of Task and building a workflow will not be restricted by this implementation guide.

HL7 guidance materials for designing request workflows:

- Workflow
- Workflow module
- Additional explanations - WIP

### Medication: identifier, code, classification

In the case of medications, the distinction between .identifier and .code is not always clear, and practices for using these elements vary across countries. This implementation guide allows the use of the .identifier element for non-instance identifiers, such as IDMP identifiers or product codes from a national product registry or the EMA PMS.

A product code is typically used when the source of the data is distributed as a code system. This may include SNOMED CT, a national drug extension, or any local code system supporting prescribing and dispensing use cases. It is common to prescribe products at the virtual product level and dispense them at the branded product package level. The source system for virtual products may differ from the source system for branded products.

The implementation guide introduces an extension for classification and recommends using it for ATC as well as for any local classifications relevant to the use case. In several countries, ATC is also known to be added to the .code element as an additional coding. This practice is not prohibited by the implementation guide. However, implementations must be able to distinguish the actual prescribed concept from classification codes to remove potential ambiguities in cross-border settings.

### Data absent reason

This implementation guide does not use data absent reason extensions in profiles.
Handling missing data is explained in HL7 Europe Base and Core FHIR Implementation Guide.