HL7 (Health Level Seven International) is a set of standards, formats and definitions for exchanging and developing electronic health records (EHRs). HL7 standards, developed and promulgated by the healthcare IT standard-setting authority HL7 International are the de facto standards in healthcare IT, though some HL7 users have called on Congress to create stronger legal interoperability standards for the healthcare IT industry.
A nonprofit organization with members in more than 50 countries, HL7 was founded in 1987 and accredited by the American National Standards Institute in 1994. It develops new standards using a multi-year balloting system in which members vote and add commentary in successive balloting rounds until negative comments are eliminated and draft standards and draft standards for trial use (DSTU) are commonly agreed upon. HL7 also promotes global interoperability in healthcare IT by providing guidance about how to implement its standards. The "7" in the organization's name refers to Layer 7 in the Open Systems Interconnection (OSI) reference model. Layer 7 is the final layer -- the application layer -- in the communication model the International Organization for Standardization developed for OSI.
Health Level 7 standards define and provide formats for messaging and data exchange, decision support, rules syntax and common health data definitions in clinical documents and EHR and personal health record (PHR) claims attachments, quality reporting, product labels for prescription medications and clinical genomics.
Several HL7 standards -- including Clinical Document Architecture (CDA) and Continuity of Care Document (CCD) -- are referenced in federal regulations associated with the U.S. Department of Health and Human Services' program for meaningful use of electronic health records.
The main HL7 standards are:
- HL7 Version 2, the most widely used messaging standard for exchange of patient care and clinical information. It is a database query language that enables healthcare providers to send messages requesting and containing health data.
- CDA, an ISO-approved standard that constitutes an exchange model for clinical documents such as discharge summaries and progress notes. Associated with the CDA are the CCD, a record of patient discharge and admission among separate facilities, and the Consolidated CDA (C-CDA), which is used in ONC meaningful use-certified EHRs to consolidate nine previous CDA templates into one document.
- EHR-PHR System Functional Models provide common language parameters for developing EHR systems and their components. The PHR Functional Model is a draft standard for functions that should be in a PHR and for data exchange between PHRs and EHRs.
- Fast Health Interoperability Resources (FHIR), a DSTU that underwent its first balloting round in spring 2015. It is a Web-based exchange language that makes interoperable healthcare applications faster, simpler and easier to write.