HL7s

HL7s refer to the standards and activities of HL7 International, a nonprofit organization that develops a framework for the exchange, integration, sharing, and retrieval of electronic health information. Founded in 1987 as Health Level Seven, the group creates specifications used by hospitals, clinics, laboratories, and software vendors to enable interoperability across disparate IT systems.

HL7's standards cover messaging, documents, and data representations. The best-known families are HL7 Version 2 (V2), a widely deployed messaging schema used for patient admissions, orders, and results; HL7 Version 3 (V3), which is more formal and model-driven using the Reference Information Model but has seen slower adoption; the Clinical Document Architecture (CDA), a document-based standard for structured clinical documents; and the more recent Fast Healthcare Interoperability Resources (FHIR), a modern, web-friendly standard built around reusable resources and RESTful APIs.

HL7 standards are designed to support semantic interoperability through linkage to standard terminologies such as LOINC for laboratory tests and SNOMED CT for clinical concepts, along with ICD for diagnoses. Implementation guides and profiling help specify how to use HL7 in particular contexts. Conformance testing and certification programs exist to verify that systems can exchange data according to HL7 specifications. HL7 collaborates with other standards groups and frameworks, including IHE, to harmonize practices.

Adoption of HL7 standards varies by region and sector, but they underpin most health information exchanges worldwide. They are maintained by HL7 International through member-driven workgroups and governing bodies, with regular releases and updates to address emerging needs in areas such as patient data exchange, interoperability, privacy, and security.