Project Background

Canada is undertaking a nationwide initiative to improve health system interoperability, ensuring that health information can flow efficiently and securely across platforms. Seamless data exchange is essential for delivering coordinated, high-quality care—especially as patients move between providers and across jurisdictions. However, many health systems remain fragmented. Electronic medical records, hospital information systems, provincial repositories, and digital health applications often operate in isolation. This lack of integration has real-world consequences: providers lack a complete view of a patient’s medical history, patients encounter barriers when trying to access their own records, and critical information may be lost or delayed during care transitions.

To address these challenges, Canada Health Infoway, working in partnership with provinces and territories, is advancing a national strategy focused on two priority areas identified through extensive stakeholder consultations:

• Secure sharing of patient summaries across systems to support transitions of care and enable cross-jurisdictional access to essential health information
• Secure messaging between solutions to facilitate safer, more efficient communication among care providers across the circle of care (e.g., provider-to-provider electronic exchanges)

The pan-Canadian FHIR Exchange (CA:FeX) specification is a foundational component of this strategy. It provides a minimally viable, FHIR-based framework that supports two key exchange patterns:

• Document exchange, such as sharing patient summaries as FHIR documents
• Discrete resource retrieval using RESTful FHIR APIs to access individual health record entries.

Development Process and Rationale

The development of CA:FeX was driven by the need to modernize health information exchange in Canada and align with global interoperability best practices, while addressing the specific needs of local implementers. Where possible, existing IHE profiles that align with CA:FeX use cases and requirements were adopted directly. In other cases, localization was required where legacy profiles did not fully meet Canadian requirements or needed refinement to better support implementation in the Canadian context.

Assessment of Existing Standards

A review of legacy IHE profiles for document exchange revealed that existing guidance is largely designed for non-FHIR-based infrastructures or supports only limited use of FHIR resources. As the Canadian market moves toward modern, RESTful FHIR exchanges, these legacy profiles do not fully address emerging requirements. The following two IHE profiles were considered during the development of CA:FeX, along with a summary of their limitations:

• Cross-Enterprise Document Sharing (XDS) is an IHE profile that defines a standards-based approach for document sharing within non-FHIR infrastructures. While XDS was considered during the development of CA:FeX, it is not included as an option in the Reference Architecture. This decision reflects the Canadian landscape’s preference for adopting more modern, FHIR-based exchange approaches.

• Mobile Access to Health Documents (MHD): is an IHE profile that uses the FHIR standard to enable document exchange, including optional support for acting as a proxy to XDS-based systems. MHD leverages FHIR resources such as List and DocumentReference to allow clients to locate and retrieve documents in a standardized way. To maintain independence from underlying storage infrastructures, whether based on XDS, FHIR, or other systems, the profile constrains the use of these FHIR resources to ensure consistent behavior. MHD specifies a multi-step retrieval process (query List, then DocumentReference, then retrieve the document), which may not align with all future implementation patterns.

Clinical systems in the U.S. market are generally more familiar with MHD-like patterns for exchanging C-CDAs over FHIR, largely due to the widespread adoption of XDS infrastructure. Many organizations that had previously invested in XDS chose to implement a FHIR façade to enable C-CDA retrieval, using MHD and related IHE profiles as the enabling mechanism. As a result, these systems are now exploring how to extend their existing configurations to support the search and retrieval of other types of documents in a similar fashion.

Systems serving non-U.S. markets, or newly developed solutions built natively on FHIR for document exchange, may lack the historical context that would otherwise prompt investment in supporting advanced search capabilities. Recently, new FHIR operations have been introduced that offer more lightweight alternatives, potentially reducing the effort required to enable richer search functionality. However, these emerging patterns are still evolving, and their applicability within the Canadian market has yet to be fully assessed.

Market Scan and Feedback from Early Implementers

Recognizing the limitations of existing IHE profiles, a market scan was conducted to evaluate patterns used in current RESTful FHIR implementation guides (e.g., US Core, IPA, PACIO, IPS). Insights from this review, combined with feedback from the Canadian implementer community, directly informed the development of the initial release of the Canadian FHIR Exchange (CA:FeX) Specification.

A key motivation behind CA:FeX is to address gaps faced by “FHIR-first” implementers when working with existing document exchange standards such as MHD and XDS. One of the central challenges is finding the right balance between enabling effective, consistent search patterns and minimizing the overhead of generating supplementary metadata (e.g., DocumentReference) required for more targeted discovery.

Feedback from Canadian implementers highlighted the following needs:

• While profiles like MHD provide useful functionality, they introduce additional steps that may not be necessary in all scenarios.
• Simpler patterns for submitting, searching, and retrieving FHIR documents and resources would better support adoption and interoperability.
• Flexibility is essential, as not all systems require the same level of metadata detail or multi-step discovery workflows.

Stakeholder Engagement and Iterative Development Process

The CA:FeX Interoperability Specifications were developed through a combination of international research and extensive consultation with health information exchange (HIE) subject-matter experts. The specifications were iteratively socialized and validated with jurisdictions and vendors through Coordinating Table and Executive Table meetings, stakeholder workshops, and targeted one-on-one engagements.

A use case-driven approach was applied in developing the specifications, following these key steps:

• Baseline: Define foundational use cases, scenarios, and business requirements for FHIR-based health information exchange.

• Collaborate: Work with jurisdictions, clinical and technical subject-matter experts, vendors, and other stakeholders to co-develop and refine detailed artifacts.

• Review: Facilitate workshops and feedback sessions to gather input and validate specifications.

• Publish: Release artifacts for broader stakeholder review and consultation.

• Recommend: Advance refined artifacts for formal endorsement and approval.

• Iterate: Continuously improve the specifications based on testing outcomes and evolving implementation needs.

CA:FeX Versioning and Releases

CA:FeX v1.0.0 Trial Implementation

Given the focus of early implementers to exchange patient summaries as a FHIR Document, CA:FeX 1.0.0 Trial Implementation was scoped to outline simple exchange patterns that allow for the search, retrieval, and submission of FHIR Documents. There are multiple ways in which documents can be formatted and interacted with in the RESTful paradigm. To read more about the various ways in which documents may be formatted, see Document Exchange and the CA:FeX Whitepaper.

Details regarding CA:FeX v1.0.0 Trial Implementation and its earlier releases can be found here.

CA:FeX v2.0.0 DFT

CA:FeX v2.0.0 DFT expanded on CA:FeX v1.0.0 Trial Implementation and provided additional guidance on the initial set of Search Parameters and resource exchange capabilities that FHIR Servers in Canada are expected to support. This release also explored an initial set of Operations that are expected to provide value to early implementers.

Implementers are encouraged to read Scope and Relationship to Other Specifications as a preface to the technical guidance in this implementation guide.

CA:FeX v2.1.0 DFT

CA:FeX v2.1.0 DFT focused on refining v2.0.0, streamlining content, and helping implementers identify which parts of the specification apply to their context.

Current Release

This release aims to provide the following:

• Offer a structured approach to FHIR-based exchange workflows by clarifying actors and conformance options for different implementation contexts.
• Improve clarity around document exchange versus discrete data exchange options.
• Ensure alignment with:
  • International Standards International Patient Access and Mobile Access to Health Documents
  • Canadian Standards: CA:Core+

The intent of CA:FeX is to support exchange behaviors in pan-Canadian specifications like the pan-Canadian Patient Summary Interoperability Specifications (PS-CA), an implementable, testable specification, based on the IHE International Patient Summary specification and the HL7 IPS Implementation Guide. The PS-CA references the CA:FeX Interoperability Specifications as an optional implementation pattern for submitting, searching and retrieving a Patient Summary document. As pan-Canadian specifications increase, particularly ones that rely on exchange of individual FHIR resources, utilization of CA:FeX is also expected to evolve.

Feedback

To provide feedback on the CA:FeX specification, please review the following page to obtain access to the Jira project: pan-Canadian Interoperability Specifications Feedback - Pan Canadian Interoperability - InfoScribe (infoway-inforoute.ca)