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CQL - Clinical Quality Language

Clinical Quality Language (CQL) is a Health Level Seven International (HL7info-icon) authoring language standard that’s intended to be human readable. It is part of the effort to harmonize standards used for electronic clinical quality measures (eCQMs) and clinical decision support (CDS). CQL provides the ability to express logic that is human readable yet structured enough for processing a query electronically. CQL is the expression logic used in Health Quality Measureinfo-icon Format (HQMF) beginning with the eCQMsinfo-icon intended for implementation in calendar year 2019. CQL replaces the logic expressions previously defined in the Quality Data Model (QDM). Begining with v5.3, QDM includes only the conceptual model for defining the data elements (the data model). Measure authors with access to the Measure Authoring Tool (MATinfo-icon) can use the tool to author measures using CQL. Visit the MAT webpage for more information.  

CQL allows for a more modular, flexible, and robust expression of the logic. It allows logic to be shared between measures and with decision support. Learn more about the advantages of CQL from the Benefits of CQL presentation.

Find the CQL Standards

CQL Standards are located on the HL7 Website: CQL Specification.

eCQM Known Issues (Standards, Tooling, and Measure Authoring) are found on the CQL Formatting and Usage Wikiinfo-icon.

Find the CQL-based QDM Reference

QDM versions for use with Clinical Quality Language (CQL) are found on the QDM page.

CQL Style Guide provides examples to standardize expression of measure concepts across eCQMsinfo-icon and define a uniform “look and feel” to eCQMinfo-icon logic using CQL. The guide focuses on a set of common best practices implemented across CQL-based eCQMs in CMS reporting programs and also promotes the use of consistent language within the framework of CQL, including libraries, aliases, definitions, functions, and conventions.

CQL Formatting and Usage Wiki serves as a collaborative workspace for the development of CQL formatting conventions and usage patterns for the representation of logic within quality measuresinfo-icon. All users have edit rights to be able to submit edits, add comments and concerns. Items on the Wiki are a work in progress and subject to change. 

CQL Online is an open source educational tool that provides a "sandbox" where eCQM developers and implementers can "play" with CQL. The tool allows users to get a feel for what CQL looks like and how to write proper expressions in this new and powerful language. More specifically, it is a syntax directed editor for writing expressions in CQL. 

GitHub Tools Repository contains tools in support of CQL, such as the CQL-to-ELM Translator used by implementation vendors.

CQL-to-ELM Translator Reference Implementation - The HL7info-icon CQL specificationinfo-icon defines both a high-level, author friendly syntax for expressing clinical knowledge, as well as a machine friendly, syntax-independent canonical representation of clinical knowledge called Expression Logical Model (ELM). The high level syntax is designed to support measure and decision support authors, while the canonical representation is designed to support point-to-point sharing and machine processing applications.

Visit the CQL Q&As page to review common questions and answers on CQL.

Visit the eCQI Tools & Key Resources Library for a complete list of tools and resources used with eCQMs and eCQIinfo-icon.

Visit the CQL Formatting and Usage Wiki. The Wiki serves as a collaborative workspace for the development of CQL formatting conventions and usage patterns for the representation of logic within quality measuresinfo-icon. All users have edit rights to be able to submit edits, add comments and concerns. Items on the Wiki are a work in progress and subject to change. The Wiki also includes a listing of known eCQMinfo-icon issues (Standards, Tooling, and Measure Authoring), users can “watch” the eCQM Known Issues page to receive email notification as issues are added and updated. 

Join the CQL Technical Chat Discussion.

Participate in an upcoming HL7 CDS Workgroup call. This Work Group discusses CQL in the HL7info-icon Clinical Quality Frameworkinfo-icon - on-Fast Healthcare Interoperability Resources (CQF-on-FHIR).

Add to or review the CQL STUinfo-icon comments on the HL7 website (search for CQL to view the comment page for the most current version of the standard).

Submit feedback on CQL issues, comments, and questions to the ONC JIRA CQL Issue Tracker.

Last Updated: February 20, 2019