Clinical Quality Language STU3 Ballot (1.3)
Clinical Decision Support Work GroupMaturity Level: 4Ballot Status: STU 3

Clinical Quality Language (CQL)

HL7 Standard: Clinical Quality Language Specification, Release 1 STU3 (CQL 1.3)

May 2018

HL7 STU Specification

Clinical Quality Language (CQL) is a high-level, domain-specific language focused on clinical quality and targeted at measure and decision support artifact authors.

In addition, this specification describes a machine-readable canonical representation called Expression Logical Model (ELM) targeted at implementations and designed to enable sharing of clinical knowledge.

NOTE To Reviewers:

A summary of changes to this version can be found in the Version History, and a detailed listing of changes is available in the 1.3 Change Log.

In addition, we are considering a breaking change to the query syntax and seeking feedback on the change. Please review and provide comments on this change:

Organization of this Specification

The organization of this specification follows the outline of the perspectives discussed in the Approach section—conceptual, logical, and physical. Below is a listing of the chapters with a short summary of the content of each.

Chapter 1 – Introduction provides introductory and background material for the specification.

Chapter 2 – Author’s Guide provides a high-level discussion of the Clinical Quality Language syntax. This discussion is a self-contained introduction to the language targeted at clinical quality authors.

Chapter 3 – Developer’s Guide provides a more in-depth look at the Clinical Quality Language targeted at developers familiar with typical development languages such as Java, C#, and SQL.

Chapter 4 – Logical Specification provides a complete description of the elements that can be used to represent quality logic. Note that Chapters 2 and 3 describe the same functional capabilities of the language, and that anything that can be expressed in one mechanism can be equivalently expressed in the other.

Chapter 5 – Language Semantics describes the intended semantics of the language, covering topics such as data layer integration and expected run-time behavior.

Chapter 6 – Translation Semantics describes the mapping between CQL and ELM, as well as outlines for how to perform translation from CQL to ELM, and vice versa.

Chapter 7 – Physical Representation is reference documentation for the XML schema used to persist ELM.

Appendix A – CQL Syntax Formal Specification discusses the ANTLR4 grammar for the Clinical Quality Language.

Appendix B – CQL Reference provides a complete reference for the types and operators available in CQL, and is intended to be used by authors and developers alike.

Appendix C – Reference Implementations provides information about where to find reference implementations for a CQL-ELM translator, a CQL Execution Framework for JavaScript, and other related tooling.

Appendix D – References

Appendix E – Acronyms

Appendix F – Glossary

Appendix G – Formatting Conventions

Appendix H – Timing Interval Calculation Examples

Appendix I – FHIRPath Function Translation