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VSAC Support Center

VSAC Frequently Asked Questions

The Value Set Authority Center (VSAC) provides downloadable access to value sets designed for many purposes and programs, including all official versions of vocabulary value sets contained in the Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) Value Sets. Each value set consists of the alpha-numerical values (codes) and human-readable names (terms), drawn from standard vocabularies such as SNOMED CT®, RxNorm, LOINC, and ICD-10-CM, which are used to define clinical concepts used in clinical quality measures (e.g., patients with diabetes, clinical visit) and other health program implementations.

The Value Set Authority Center (VSAC) provides value set search, retrieval and download capabilities through a Web interface and APIs. The VSAC provides authoring and validation tools for creating new and revising published value sets. The VSAC also integrates a Collaboration Tool for value set authors and their collaborators and subject matter experts to collectively discuss and approve their value sets.

The VSAC currently serves as the authority and central repository for the official versions of value sets that support Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) value sets.

Through the VSAC, NLM draws upon its responsibility as the central coordinating body for clinical terminology standards within the Department of Health and Human Services (HHS) to assure the ongoing validity and accuracy of the value sets.

Value sets are lists of specific values (terms and their codes) that define clinical concepts derived from standard vocabularies to support effective health information exchange. Among other use cases, a value set may act as a data element of allowed values that define a patient population (e.g., patients with diabetes, clinical visit, or reportable diseases) that should be included in the numerators and denominators when computing a clinical quality measure.

Yes. The only requirement for accessing VSAC and searching value sets is a free Unified Medical Language System® Metathesaurus License. If you do not have a UMLS License, request one here.

The VSAC Support Center page has a link to the VSAC Release Notes Archive. Here you can find VSAC Release Notes dating back to January 2015. You may also subscribe to the VSAC Updates listserv for timely VSAC announcements, changes, and news.

A list of the available VSAC code systems and their versions can be found on the Code Systems and Tools page, along with direct links to each code system supplier.

According to the Centers for Medicare and Medicaid Services, "Electronic Clinical Quality Measures, or eCQMs, are tools that help us measure and track the quality of healthcare services provided by physicians, nurses, hospitals and others in our health care system. These measures use a wide variety of data that are associated with a provider's ability to deliver high-quality care or relate to long term goals for health care quality. eCQMs measure many aspects of patient care including: health outcomes, clinical processes, patient safety, efficient use of healthcare resources, care coordination, patient engagements, population and public health, and clinical guidelines."

The Data Element Catalog, linked from the VSAC home page, contains the complete list of Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) Value Set names.

Sign in to VSAC with your UMLS username and password. If you do not have a UMLS License, you may request one free of charge here. In the VSAC Download tab, you will find the prepackaged downloadable files for all official versions of the Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) Value Sets for reporting periods from 2014 to the present. We offer these downloadable packages in both Excel and XML formats, and we offer these value sets sorted by CMS ID, Value Set Name, and Quality Data Model (QDM) Category.

Machine-readable files: In addition to the Excel and XML file formats we provide, the VSAC Downloads tab offers "SVS (text)" (pipe-delimited) files that users have requested for machine-readable and import friendliness. Many users also rely on the Excel format for machine import, as Excel allows you to export as delimited text files: File-->Export-->Change File Type-->Text (Tab delimited), CSV(comma delimited), Formatted Text (space delimited).

The VSAC Collaboration Tool is an Alfresco© content management system for value set collaboration, communication, workflow and document management by value set authors, stewards, and their invited external collaborators. Value set authors and stewards can post value sets from the VSAC Authoring Tool into VSAC Collaboration to be viewed, discussed, or approved by their collaboration group members.

For more information, please see the VSAC Collaboration Tool User’s Guide page.

It depends on the code system and whether NLM finds any issues with the data provided by the code system provider. In most cases, barring any data issues or inconsistencies that require resolution, VSAC can provide code system updates on the third Monday of the month when given at least two weeks' notice from the content provider. This is the time it takes VSAC to extract, transform, load, and perform quality assurance for the code system. For example, if the US Edition of SNOMED CT releases on 09/01/2016, we are likely able to provide this release in VSAC by the third Monday of September, 9/19/2016.

For specific questions and guidance related to the measure logic and content of the eCQM value sets, please submit a request to the ONC Project Tracking System at Although NLM hosts the repository for value sets (VSAC), including value sets specified in eCQMs, and NLM is the central coordinating body for clinical standard terminologies (SNOMED CT, RxNorm, LOINC), NLM does not create the rules, measures, guidance or value sets for the measures.

After you sign in to VSAC, using your UMLS credentials, click on the Search Value Set tab. You can search by text words, codes, value set IDs (OIDs) and you can narrow your search results by selecting from pull-down menus for Code Systems, Meaningful Use Measures and other filters on the left sidebar. Please see the Search VSAC page for more information.

When you are updating a previously published value set, select 'New Version', which will use the existing value set ID (OID) for that value set.

If you select ‘Clone,’ you are creating a new value set with a new OID, for a new purpose. You might want to use Clone when you find a value set that is close to what you want to use for your purposes, but you want to revise it in some way for a new purpose. You should not use Clone for updating published value sets. See this tutorial: Updating Value Sets

  • Sign in to VSAC. Click on the ‘Search Value Sets’ tab.
  • Select the ‘Code System’ of interest in the filter pull down menu on the left and click the ‘Apply Filters’ button.
  • In the Query box, enter the code of interest and click ‘Search’ or hit the ‘Enter’ key on your keyboard.
  • Click on the hyperlinked OID of any of the value sets retrieved. This will take you to the Value Set Details display.
  • Click on the Measure button to display the information about which Clinical Quality Measure uses the selected value set.

Sign in to VSAC with your UMLS username and password. If you do not have a UMLS License, you may request one free of charge here. In the VSAC Download tab, you will find the prepackaged downloadable files for all official versions of the Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) Value Sets for reporting periods 2014-2017. We offer these downloadable packages in both Excel and XML formats, and we offer these value sets sorted by CMS ID, Value Set Name, and Quality Data Model (QDM) Category.

NLM has implemented the Sharing Value Sets (SVS) Technical Framework (PDF). Alternatively, users may wish to use a Common Terminology Services 2 (CTS2) based service maintained by Mayo Clinic to access NLM VSAC value set data.

Centers for Medicare and Medicaid Services (CMS) provide the official source for clinical quality measures that are required for Eligible Professionals (EP) and Eligible Hospitals (EH) to meet Meaningful Use (MU). CMS is the source of truth for these Clinical Quality Measures.

VSAC offers a Downloadable Resources Table, accessible from the Download tab on the VSAC home page, that provides prepackaged downloads for the most recently updated and released Centers for Medicare & Medicaid (CMS) Electronic Clinical Quality Measure (eCQM) value sets, as well as for previously released versions of these value sets.

Agency for Healthcare Research and Quality (AHRQ) offers the United States Health Information Knowledgebase (USHIK) as an authoritative one-stop shop for public access to Meaningful Use quality measure components. USHIK provides technical specifications for the CMS eCQMs including their descriptions, computation logic, data elements, context, version comparisons, and value sets. USHIK provides measures and value sets in Excel, PDF and XML.

The Unified Medical Language System® Metathesaurus License, available from NLM, is required for these resources at both VSAC and USHIK.

Value set definitions include characteristics that an author uses to describe a value set. The extensional value set definition includes the author’s enumeration of terminology codes defined by the value set. Future development will enable authors to intensionally define value set terminology code content as a logical statement (e.g., all codes that are descendants of this code). Value set definitions exist only in the VSAC Authoring Tool. Value set metadata, which are part of the overall value set and not linked to the value set definition, include the following elements: value set name, value set OID, note, purpose statements, author group, and steward group.

Value set expansions are computed by VSAC algorithms from each value set definition, created by authors in the VSAC Authoring Tool, using an author-designated expansion profile calculation of specified code system versions. The default expansion profile calculation consists of the most recent code system versions available in VSAC. Value set expansions are snapshots-in-time of value set definitions computed by VSAC using default or author-specified code system versions. Value set expansions exist only in the “Search Value Sets” tab (the public repository). VSAC will calculate value set expansions using the value set definitions chosen by the following order of priority:

  1. If a value set definition version is assigned to a release by the author/steward through the “Assign Release” procedure, VSAC expands this definition version in the release.
  2. If a value set has no user-assigned release (as in #1), VSAC will expand the value set definition version used by the previous base release.
  3. If a value set was not used in a previous/base release (as in #2), VSAC will expand the latest published definition version of the value set. Mainly, this is for new program releases and for newly created value sets for an eCQM Annual update, but it can apply to addendum work if authors need to create new member value sets for a grouping value set already specified by a measure.

An expansion profile is just a calculation that we apply to a value set to constrain it to predefined code system versions and allowed legacy codes. Our most recent expansion profile is called “eCQM Update 2017-05-01” and if you are developing and testing value sets, you should use that profile value along with parameter includeDraft=yes with the VSAC SVS API V2 to request the correct value set expansions for the upcoming April 28, 2017 eCQM release. Here is an example API call:{OID}&profile=eCQM Update 2017-05-01&includeDraft=yes&ticket={serviceTicket}
Once the value sets are published, after April 28, 2017, you need to use the version parameter instead of the profile parameter. After April 28, 2017, to return a published expanded value set with version="eCQM Update 2017-04-28" use the following API call:{OID}&version=eCQM Update 2017-04-28&ticket={serviceTicket}
See the API documentation for more information.

For example, your value set export from VSAC is not showing the correct code system version you expected for the MU2 Update 2015-05-01 Expansion Profile. The Export Value Set Details (Excel) link at the top of your editing screen will always return the VSAC Auto Expansion that uses the most recent code systems available in VSAC, and this is not what you want in this case. In the editing screen for your value set, at the top of your Value Set Code List:

  1. Click the Validate link.
  2. In the Code Validation pop-up window, Select Expansion Profile: MU2 Update 2015-05-01.
  3. To download an Excel spreadsheet based on this correct expansion profile, click the Export Expansion Details (Excel).
  4. This spreadsheet includes a tab that lists all the code system versions used by this expansion profile.

Please contact us if you believe you should be able to edit or make new versions of a value set and VSAC is not allowing you to do so. This is likely due to Author or Steward group permissions with the VSAC database. We can fix these permissions quickly if you let us know about them.

Based on prior guidance to use generic drug identifiers for medication products, the eCQMs only reference the branded generic terms in RxNorm. This is in part to avoid the maintenance involved given the annual basis on which the measure value sets are published-- it would lead to many more outdated brand drug references. If your system references drug brand codes, it is necessary to remap the brands to the generic drug codes to report the quality measures.

There are three types of value sets: Extensional, Grouping, and Intensional. Intensional value set functionality is under development and not yet available in VSAC.

Extensional Value Set: A set of concept codes and descriptors, in the form of an enumerated list, selected to serve a specific clinical purpose. An enumeration of concepts is not always an ideal approach to define a value set, as a comprehensive approach to clinical quality measure development dictates examination of complete code hierarchies in a code system to define the levels of concept inclusion (see Intensional Value Set, below). An extensional value set in VSAC contains codes from only one code system.

Grouping Value Set: A list several value sets that share a common purpose and similar clinical concepts. For Meaningful Use Clinical Quality Measures, specifically, members of a grouping value set must have the same Quality Data Model Category, but the value set members of the grouping do not need to share the same code system. For example, the "Wound Care" grouping value set used in measure CMS188v6 groups together three value sets: Wound Care I9, Wound Care I10, and Wound Care SM CT, all of which relate to wound care.

Intensional Value Set: A list of codes based on a logical statement that often has an algorithmic basis for selection of concepts. For example, "include all concepts that are children of a parent concept" in a hierarchical code system. Intensional value set functionality is under development and not yet available in VSAC.

For more information, please see the VSAC Authoring Best Practices page.

The Purpose Statement is a multi-part free-text mandatory entry. It provides a clear and comprehensive description of the code membership and purpose of the value set. This important metadata element must take into account how the members will be used in a clinical measure or in any other intended application. The Purpose Statement cannot be validated automatically, so authors should spend time to make this text as informative as possible for human readers to understand the author's intent of the value set, and how the value set is put together. To avoid redundancy, there should be only one value set for a given purpose.

For published value sets: Search Value Sets → Select OID → Select the Contact icon.

For value set authors working within the Authoring Tool: Authoring tab → My Value Sets → Select OID → Left side bar: Contact Steward

Access to the Value Set Authority Center requires a free Unified Medical Language System® Metathesaurus License. Please note it may take 1-5 business days to obtain a license.

After your license has been approved, go to the VSAC home page and click 'Sign In' with your UMLS username and password.

Authors create, edit, and submit value sets to a designated Steward.

Stewards approve, reject, and publish submitted value sets from Authors.

For more information on the specific roles and functions of authors and stewards, please see the VSAC Author and Steward Roles page.

To become a VSAC Author or Steward you first need a free Unified Medical Language System® Metathesaurus License. You will then need to submit an Author Registration request using the NLM Customer Service e-mail form. For details on requesting author and steward permissions, please see the VSAC Author Registration page.