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The National Library of Medicine’s Value Set Authority Center (VSAC) is a crucial resource for healthcare professionals, researchers, and informaticists involved in clinical quality measurement and health information exchange. VSAC provides authoritative access to value sets—standardized lists of clinical terms that define specific medical concepts used in electronic health records (EHRs), clinical guidelines, and quality reporting. Managed by the National Library of Medicine (NLM), VSAC supports the development, storage, and distribution of value sets that help ensure consistency and interoperability in healthcare data. These value sets are essential for ensuring that health IT systems can accurately capture, analyze, and report medical conditions, treatments, and outcomes across different platforms and institutions.

Photographer’s Mate Airman Apprentice Ricardo Reyes, Public domain, via Wikimedia Commons
Image credit: Photographer’s Mate Airman Apprentice Ricardo Reyes, Public domain, via Wikimedia Commons

Through VSAC, users can search for, download, and maintain value sets used in various federal initiatives, such as the Centers for Medicare & Medicaid Services (CMS) clinical quality measures and the Office of the National Coordinator for Health Information Technology (ONC) standards. The platform also offers tools for value set creation and maintenance, allowing healthcare professionals to curate custom lists that align with evolving clinical and regulatory requirements. By facilitating standardized terminology usage, VSAC helps improve data quality, enhances patient care, and supports meaningful use of EHRs across diverse healthcare environments.

The cql-exec-vsac module serves as a VSAC-enabled code service within the JavaScript CQL Execution project, enabling seamless execution of Clinical Quality Language (CQL) queries that reference Value Sets published in the National Library of Medicine’s (NLM) Value Set Authority Center (VSAC). This functionality is crucial for ensuring interoperability in clinical decision support and quality measurement frameworks, as it allows healthcare systems to retrieve and apply standardized terminologies in automated workflows. By integrating with VSAC, the CQL Execution Engine can dynamically fetch the necessary Value Sets, ensuring up-to-date terminology utilization without requiring manual updates.

My enhancement now extends support beyond VSAC, enabling the use of FHIR-compliant terminology servers for private or custom-defined Value Sets. This added feature allows healthcare organizations to leverage their own FHIR-based terminology repositories, improving flexibility for institutions that need localized or proprietary clinical vocabularies while maintaining compliance with existing standards. Users can specify a FHIR Base URL to direct queries toward non-VSAC terminology servers, ensuring broader accessibility to domain-specific terminologies. This advancement significantly improves data interoperability, making CQL execution more adaptable across diverse healthcare environments.

In Part 3, I will discuss medpromptjs, a JavaScript library that implements LLM-in-the-Loop pattern.

Bell Eapen
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