Exchanging Data & Documents in FHIR

Overview

The CA:FeX specification package was developed to define and guide approaches to information sharing using FHIR RESTful capabilities primarily for (but not limited to) greenfield implementations. Expectations in CA:FeX will be rooted in best practices from international FHIR specifications (e.g., IPA, QEDm, US Core, IPS, etc.) that are feasible for the Canadian market to standardize around.

At a glance, CA:FeX will provide guidance in the following areas:

• Single Resource Exchange: RESTful exchange behaviors and identification of the capabilities (read, search, create, update, and delete) and subset of FHIR resource types that systems are expected support single resource exchanges
• Multiple Resource Exchange: Approaches for exchanging multiple resources together in the form of documents, and identification of standardized search parameters and practices for document implementers to incorporate into guides and systems
• Extending APIs with FHIR Operations: Identification of functional FHIR operations that allow implementers to abstract complexity away from requesting applications, by offering a single API call that can trigger multi-step processes to execute

The CA:FeX specification package is intended to act as a key building block within the arsenal of interoperability tools that provide vendors with the ability to anticipate or predict the minimum expectation to interact with any ecosystem interface, regardless of jurisdiction. In line with international peers, it will act as the guidance to define “Interaction Support” for all health IT ecosystem players.

This guidance has been migrated to the Pan-Canadian FHIR Exchange (CA:FeX) IGuide.

Scope

This specification initially targeted the exchange of FHIR Documents.

The current version of CA:FeX is focused on the FHIR RESTful exchange of documents, single-resource exchange (e.g., retrieval of last 3 years of dispensed medications), and the execution of transactions. CA:FeX aims to provide clarity to implementers by identifying some of the choices currently available using FHIR, ranging from simple to a higher level of sophistication. 

Transactions

IHE Transactions are interactions between actors that communicate the required information through standards-based messages (e.g., patient look-up query, send patient summary information, etc.). Established early CA:FeX Transactions (i.e., CA:FeX-1 Submit Data, CA:FeX-2 Search Data, CA:FeX-3 Retrieve Data) were intended to be generic enough to describe the interaction pattern between actors participating in FHIR exchange. However, early scoping of CA:FeX to identify document exchange requirements resulted in a need to differentiate how the transactions could be specialized for a given context. 

For example, the search behavior and FHIR Resources making up the payload returned from a FHIR Assembled Documents Repository are expected to be different from the search behavior and payload returned from a Hybrid Documents Repository that may contain legacy Binary documents as well as FHIR Documents. This resulted in the need to specialize the transactions to describe these differences (e.g., CA:FeX-3A: Retrieve FHIR Document and CA:FeX-3B: Fetch DocumentReference).

Note: The inclusion of Single Resource Exchange and Extending APIs with FHIR Operations in the scope of this release has been introduced pre-emptively to allow the specification to scale to implementer needs. However, the need for further specialized transactions for exchange of certain types of discrete data (e.g., allergies, practitionerRole) or for certain types of FHIR Operations, is yet to be assessed. 

The following table has been provided to describe the interaction between Use Cases and Transactions. 

FHIR Version

FHIR content in this specification is based on FHIR Release 4 (v4.0.1).