Value Set Authority Center (VSAC)

The Value Set Authority Center (VSAC) is a central repository for the official versions of value sets that support the electronic Clinical Quality Measures. The National Library of Medicine (NLM) maintains the NLM Value Set Authority Center and provides downloadable access to the value sets.

Value sets are lists of specific values (terms and their codes) used to describe clinical and administrative concepts in the quality measures. They provide groupings of unique values along with a standard description or definition from one or more standard vocabularies used to describe the same clinical concept (e.g., diabetes, clinical visit, demographics) within the quality measures.

Information on how value sets are created, used, and updated is available in the VSAC Support Center.

Note: Viewing and/or downloading proprietary value sets, such as those using AMA copyrighted CPT codes or SNOMED CT codes, from NLM-VSAC or AHRQ-USHIK requires a free Unified Medical Language System® Metathesaurus License (UMLS), (available at It is expected that any use of value sets is consistent with these licensing requirements and copyright protections.

View a presentation on new VSAC tools and improvements (August 2015). 

Tool Categories

Governing Organization