Profling Principles for Medication Profiles

MedicationStatement, MedicationRequest, MedicationDispense

The ACCESS medication profiles were drafted with the following principles in mind:

Principle 1: Delineate what information is critical to citizens vs clinicians

In consultation with subject matter experts, it was determined that citizens and clinicians likely have substantially different information needs, and therefore separate profiles targeting the two groups were required. This profile focuses on the information that is critical for clinicians to understand the medications that have been dispensed or filled for their patients. This profile focuses primarily on the viewing of medication dispense information but it was made flexible enough to support clinicians creating and updating medicationDispense resources.

Principle 2: Target lossless two-way information flow

CeRX interactions have been heavily adopted by drug information systems in the Atlantic provinces and across Canada. Given the level of adoption of CeRX to exchange medication information, FHIR efforts will likely involve some transformation of source data into target FHIR elements. As applications and systems begin to adopt the FHIR profiles, it's also expected that FHIR resources may also need to be considered for transformation into target CeRX interactions (to reduce the burden on drug information systems that may not be ready to transition to FHIR).

In order to ensure adoption of the profiles in an ecosystem that will support both standards, efforts were made to preserve at least the possibility of lossless two-way exchange. Lossless two-way exchange depends in part on architectural decisions that are outside the scope of this project (and is therefore not guaranteed), however, efforts were made to outline key considerations and challenges for performing conversions between FHIR -> CeRX and CeRX -> FHIR. Those considerations can be found in the Transformation Considerations Page (insert link here).

Principle 3: Target alignment with US Core and Canadian Core profiles

Medication profiles were designed with alignment (or at least compatibility) with US Core in mind. US Core R4 Profiles were targeted for two reasons:

1. Existing adoption by US-based vendors, and
2. Their use in the efforts to establish a Canadian Core profiles

This principle was adopted with the goal to enable broader interoperability and avoid proliferation of competing standards and profiles.

Principle 4: Ensure constraint decisions are source-aware

Medication profiles prioritized FHIR elements that map to CeRX fields that are currently available across drug information systems and jurisdictions. Given that jurisdictions are currently storing and exchanging much of the medication information using CeRx interactions, FHIR efforts will likely involve some transformation of source data into target FHIR elements.

The majority of critical/must-support elements were covered in the existing mapping of CeRX elements to FHIR elements, however, some drug information systems could only support CeRX interactions that were limited in what they supported for data elements. Establishing FHIR cardinality constraints impact source systems by increasing risk of conformance errors in cases where the CeRX standard varies from the FHIR profile:

• Example 1: CeRX allows an element to be optional or populated with a null value, but the FHIR profile requires at least one value to be present (1..X FHIR cardinality)
• Example 2: CeRX allows an element to have multiple repeats, but the FHIR profile only allows one value (X..1 FHIR cardinality).

These types of CeRx cases had a major influence on the decision to not introduce additional cardinality constraints to the medication resources. Given that the ACCESS profiles will need to be flexible enough to support all Canadian jurisdictions, additional cardinality constraints are not recommended until more is known about jurisdictional implementations of CeRx outside the Atlantic provinces.

This approach maintains optionality and flexibility in the FHIR profiles and circumvents the requirement for drug information systems to dramatically modify their existing implementations of CeRX.