CQL
Clinical Quality Language – expression language used to communicate specific data to be retrieved and logic needed to evaluate eCQMs. The machine-readable Expression Logical Model (ELM) is a representation of the CQL.
Electronic clinical quality measure (eCQM) standards are critical to data consistency, validity, and interoperability. Standards, in the context of health information technology, refer to agreed-upon methods and terminology for connecting systems such as file formats for electronic documents, messages, and related health care data elements. Standards pertain to data transport, data format and structure, and the meanings of codes and terms. See the Interoperability Standards Platform for more information about eCQI standards and initiatives.
The figure depicts the use and flow of the eCQM transmission standards.
Key standards for electronic transmission of health information used to support eCQMs:
FHIR
Fast Healthcare Interoperability Resources® - a key standard under consideration for use by CMS for exchanging health care information electronically.
HQMF
Health Quality Measure Format – a standard format to describe eCQM metadata, like the numerator,
denominator, exclusions, and exceptions, using XML documents.
CQL-Based HQMF
Clinical Quality Language-Based Health Quality Measure Format – an implementation guide for how to use the HQMF base standard with QDM and CQL to author eCQMs.
QDM
Quality Data Model – a standard information model used to define and standardize data elements, attributes, and their relationships for clinical concepts used in eCQMs.
QRDA
Quality Reporting Document Architecture – standard format for reporting eCQM data in a structured, consistent representation. QRDA I is used for individual patient data and QRDA III for aggregate patient data.
Health Terminology Standards
Numerous organizations develop and maintain standard terminologies. The National Library of Medicine’s (NLM) Unified Medical Language System® Metathesaursus is a large biomedical thesaurus organized by concept, or meaning, and it links synonyms to the concept from nearly 200 different terminologies. However, eCQMs use only a handful of these terminologies, e.g., SNOMED CT and RxNorm. NLM’s Value Set Authority Center (VSAC) is the official source of eCQM value sets used in eCQMs in CMS programs.
Last Updated: Jun 17, 2025