US Core IG

The US Core Implementation Guide (IG) is a Fast Healthcare Interoperability Resources® (FHIR®) IG that establishes a baseline set of FHIR profiles and requirements to support consistent access to and exchange of health information across U.S. healthcare systems. US Core profiles define how FHIR resources are constrained for U.S. use, including requirements for data elements, extensions, terminology, and other implementation expectations. The IG also defines FHIR RESTful interactions for accessing patient data.

US Core supports implementation of the United States Core Data for Interoperability (USCDI), which defines a standardized set of health data classes and data elements for nationwide interoperable health information exchange. In simplified terms, USCDI identifies the high-level data that should be available for exchange, while US Core defines how those data are represented and exchanged using FHIR. The relationship is not always one-to-one: a USCDI data element may map to multiple FHIR elements or profiles, and US Core includes additional elements needed to make the information implementable in FHIR.