Interoperability Through Implementation Guides

Digital health is evolving rapidly, and the need to exchange health data in a consistent and secure manner is a major challenge. Fast Healthcare Interoperability Resources (FHIR) is a standard developed by HL7 to facilitate interoperability—that is, the ability of information systems to communicate with one another without special adaptation, thereby standardizing data exchange.

FHIR is a generic standard designed to cover all types of health data as well as the methods for exchanging that data. The standard is based on modular components, called “resources,” which represent a specific type of information (e.g., patient, healthcare professional, healthcare facility, etc.). When combined, these resources enable specific use cases. FHIR also offers several paradigms for exchanging resources, including the REST API and the FHIR Document.

However, most FHIR resource attributes are not mandatory, and there are no constraints on terminology; profiling allows resources to be tailored to specific use cases, including by creating extensions for business elements not natively covered by the standard. This high degree of flexibility in the use of FHIR resources does not ensure interoperability between information systems without applying constraints. This is where FHIR Implementation Guides (IGs) come into play, providing specific guidelines to ensure consistent and interoperable implementation of the FHIR standard for well-defined use cases.

What is an FHIR IG?

The FHIR documentation defines an IG as a set of rules describing how FHIR resources are used (or should be used) to solve a specific problem, accompanied by supporting documentation that clarifies their use

IGs document how profiles are created, specify how to use FHIR resources, and outline the constraints applied to meet specific needs. In addition, IGs define how to exchange information by specifying the interactions to be used in a given context.

IGs are designed to help developers and organizations deploy FHIR solutions in a consistent manner.

Key Stakeholders

Today, an IG is associated with a specific use case that has not yet been addressed by the ecosystem, whether at the national or international level. Several types of stakeholders are driving the creation of IGs: standards organizations, specialized associations, and government agencies. Here are four of these key stakeholders:

• HL7 operates on an international level. This organization develops standards such as HL7v2, CDA, and FHIR, thereby promoting the interoperability of health data worldwide. At the European level, the HL7 Europe initiative addresses European needs for standardization in the field of digital health.
• IHE (Integrating the Healthcare Enterprise) is also a major player in the field of healthcare system interoperability. It operates at the international, continental, and national levels. IHE develops specifications based on established standards such as DICOM and HL7 to facilitate the sharing of health data between different systems and stakeholders, thereby contributing to better integration of health information.
• In France, Interop’Santé is a consortium of four organizations, each working toward the standardization of information exchange in the healthcare sector:
• IHE France (French extensions)
• PN13-IS (medication management)
• HL7 France (FHIR implementation)
• HPRIM (procedure data collection and PMSI)
• In France, the Digital Health Agency (ANS) plays a key role in the digital transformation of the healthcare system. One of the main roles of this government agency is to define and oversee the Health Information Systems Interoperability Framework (CI-SIS). This framework establishes the technical and semantic rules necessary to ensure IT communication in the health, medical-social, and social sectors. Any new specification covering a new use case is published in the CI-SIS as a module. Centralizing information helps avoid redundancy in the profiles created and promotes the use of current specifications. In this way, the ANS acts as a regulator.

Benefits of FHIR GUIDELINES:

• Improved interoperability: By following guidelines, healthcare systems can exchange data more seamlessly and consistently, which improves the quality of care and operational efficiency.
• Reduced complexity: IG simplify FHIR implementation by providing clear guidelines and specific use cases. Additionally, they help developers understand how to use FHIR resources in specific contexts, thereby reducing the risk of errors and inconsistencies.
• Maintenance via Git: Managing FHIR profiles through GitHub allows you to track changes, manage versions, and collaborate effectively. This makes it easier to update profiles, correct errors, and adapt them to real-world needs, while maintaining a clear history of changes.
• Accessibility via website: FHIR profiles are published online and easily accessible via a single URL.

Disadvantages of FHIR IGs:

• Evolution and maintenance: The standard is not yet at the normative stage, meaning it is not yet stable. For resources that are not yet at the standardization stage, new updates to the standard may not ensure backward compatibility with previous versions, which may require updating the IGs. Furthermore, maintaining IGs can add an additional human and therefore financial burden for organizations, so it is important to design IGs that are easy to maintain.
• Excessive customization: While flexibility is an advantage of FHIR resources, it can also lead to excessive customization, making interoperability more complex to implement. Furthermore, the content of the IG must be precise and targeted to avoid an overload of documentation that would make information difficult to find, hence the need to impose a common structure on IGs.

Some examples of FHIR profiles:

• US Core (developed by HL7 International), which defines the minimum constraints imposed on FHIR resources to create the U.S. core profiles.
• Fr Core (developed by HL7 France), which defines the minimum set of constraints on FHIR resources to create the French core profiles.
• mCODE (Developed by HL7 International), which aims to define the structure of electronic health records in oncology.

Conclusion

FHIR IG are essential tools for standardizing and facilitating the adoption of FHIR in healthcare systems. The creation of IG is initiated by organizations and government agencies such as HL7, IHE, Interop’Santé, and the ANS, while their implementation is carried out by software vendors. IG offer numerous benefits, particularly in terms of reducing complexity, improving interoperability, and enhancing accessibility. They also present challenges, particularly regarding maintenance, since until all standard resources have reached normative status, the IGs are likely to be updated.

IGs are therefore crucial for ensuring a high level of consistency and interoperability in FHIR specifications.

👉 More information on our consulting and interoperability testing services: https://www.kereval.com/health-interoperability/

Article co-authored with Nolwenn Le Buhan and Dinan Brisson