Defining and Handling Custom Terminology in FHIR

Details

When a new project starts using a managed FHIR server, the team aims for an ideal standardized approach. However, they often encounter the problem that not every value used in their solution can be mapped to a common code system like SNOMED or LOINC. In this scenario, experts may have to define unique custom values. The article proposes addressing this by first creating a FHIR CodeSystem resource, using its URL as a unique identifier. Subsequently, it recommends updating ValueSets to combine standard codes (like SNOMED) with the necessary proprietary custom codes. The author emphasizes that while the need for custom terminology is unavoidable, when encountered, it should be formalized as early as possible and done through proper procedures. This approach, though temporarily sacrificing a degree of interoperability, is presented as a practical solution because existing code systems like SNOMED or LOINC are themselves incomplete and have slow update processes. By following these steps, proprietary terminology can be managed within the standard FHIR framework, allowing the project to proceed effectively.