CQL - Clinical Quality Language

CQL Overview Resources

Explore these resources to get an overview of CQL­ and learn how to implement CQL from experts.

• Learn more about the fundamentals of CQL and why it is important on the CQL Educational Resources page. Also find past presentations and webinars for the various audiences who might use CQL.
• Attend an upcoming Cooking with CQL, Quality Data Model (QDM), and Fast Healthcare Interoperability Resources® (FHIR®) webinar. The sessions feature open discussion from subject matter experts on the Measure Authoring Tool (MAT), show how to express measures using CQL, and review questions. Visit the Electronic Clinical Quality Improvement (eCQI) Calendar to find registration information.
• Get a good start with CQL by visiting the CQL Frequently Asked Questions (FAQs) page to review common questions and answers.
• Visit the Connect tab to find out how to connect to various CQL resources and register for upcoming CQL sessions.

CQL Tools for Implementers 

Access these tools to support your use of CQL.

• GitHub Tools Repository - Find tools in support of CQL, such as the CQL-to-Expression Logical Model (ELM) Translator used by implementation vendors.
• Explore the eCQI Tools & Key Resources Library for a complete list of tools and resources used with electronic clinical quality measures (eCQMs) and eCQI. 
• CQL-to-ELM Translator Reference Implementation - The Health Level Seven International® (HL7®) CQL specification 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 ELM. The design of the high-level ELM syntax is to support measure and decision support authors, while the design of the canonical representation is to support point-to-point sharing and machine processing applications.

CQL Resources for Authors

View these resources to learn about CQL formatting, usage, and standards.

• CQL Formatting and Usage Wiki - Visit this wiki which serves as a collaborative workspace for the development of CQL formatting conventions and usage patterns for the representation of logic within quality measures. A selection of resources found on the wiki are
  • Formatting and Usage Topics
  • Cooking with CQL Examples and CQL Questions and Answers (Q&As)
• CQL Standard - Visit the HL7 Website to access the CQL Specification.
• CQL Style Guide (v6) provides guidance to measure developers for authoring measure expressions and using functions, libraries and definitions for calendar year 2023 reporting. Modifications to the Style Guide include references to the HL7 CQL standard, the HL7 CQL-based Health Quality Measure Format (HQMF) implementation guide, and input from standards owners and measure developers to refine CQL expression. The purpose of the Style Guide is to standardize expression of measure concepts across eCQMs and define a uniform “look and feel” to eCQM logic using CQL. The guide focuses on a set of common best practices implemented across CQL-based eCQMs in CMS quality reporting programs. The Style Guide also promotes the use of consistent language within the framework of CQL, including libraries, aliases, definitions, functions, and guidance on other conventions, such as operator precedence. Measure stewards and measure developers who are developing or specifying eCQMs for future inclusion in CMS programs should align with these best practices.

CQL Archived Resources

• CQL Style Guide (v5) aligns with the CQL expression style of eCQMs using CQL for calendar year 2022 reporting.
• CQL Style Guide (v4) aligns with the CQL expression style of eCQMs using CQL for calendar year 2021 reporting.
• CQL Style Guide (v3) aligns with the CQL expression style of eCQMs using CQL for calendar year 2020 reporting.
• CQL Style Guide (v2) aligns with the CQL expression style of eCQMs using CQL for calendar year 2019 reporting.