Value Set Information

Value sets are a list of codes drawn from one or more code systems, where the concepts included share a common scope of use. The codes and corresponding terms come from standard clinical vocabularies (such as Current Procedural Terminology [CPT], Systematized Nomenclature of Medicine Clinical Terms [SNOMED CT], RxNorm, and Logical Observation Identifiers Names and Codes [LOINC]) and define clinical concepts to support effective and interoperable health information exchange. Value set authors use value sets in quality measures and clinical decision support to gather all relevant coded concepts from clinical or administrative data, define patient or encounter populations for analysis, and support condition-specific diagnostics and order sets.

Value sets have a life cycle similar to many persistent objects. The Value Set Authority Center (VSAC) is a tool suite developed by the National Library of Medicine to support the creation, maintenance, and retrieval of value sets. The VSAC serves as the central repository for the CMS electronic clinical quality measure value sets. However, other value set repositories are available, such as the Public Health Information Vocabulary Access and Distribution System. 

The VSAC Support Center provides online information about VSAC access, value set lifecycles and workflow, measure developer and steward roles, and best practices for value set development. In addition, the VSAC Support Center offers archived users’ forums and release notes and provides links to VSAC publications.

Coded Data Elements

Coded data elements in quality measures are bound to (i.e., may use) either

• A single, specific code from a code system that is referenced directly in the measure and is not a value set; it is considered a direct referenced.

OR

• A value set (i.e., a set of codes) where each code is equivalent with respect to use in the context of that data element.

In quality measures, codes in value sets identify the specific clinical concepts (for example patients, encounters, procedures, diagnoses, medications, or results) that should be considered with respect to the measure data element using the value set.

Value Set Creation Methods

Value set authors can create value sets using several methods:

Extensional:

A set of concept codes and descriptors in the form of an enumerated list. An extensional value set in the VSAC contains codes from only one code system.

Intensional:

A list of codes based on a logical statement that often has an algorithmic basis for the selection of concepts based on concept properties or relationships as defined within the code system. An intensional value set in the VSAC contains codes from only one code system.

Grouping:

A collection of one or more value sets that, when combined, meet the requirements of the grouping value set purpose. Value set authors often use grouping value sets in the VSAC to combine member value sets from different code systems so the grouping value set expansion set includes concepts from multiple code systems. In the VSAC, grouping value sets cannot contain other grouping value sets.