Skip to main content

CQL Clinic

Learn Clinical Quality Language (CQL) hands-on. Ten interactive lessons take you from basic data types to building a real CMS-style quality measure — write CQL, run it against synthetic FHIR patients in your browser, and get instant feedback on every expression.

info

First lesson load takes ~30–60 seconds for Pyodide to bring up FHIR4DS + DuckDB-WASM (subsequent lessons reuse the engine). Your progress is saved in the browser.

Curriculum​

  • Beginner — data types, comparisons, FHIR queries, strings & conversions.
  • Intermediate — null safety & three-valued logic, quantities & units, temporal logic, terminology (codes & code systems).
  • Advanced — query syntax (where/return/let/sort), and the capstone: build an eCQM with Initial Population, Denominator, Exclusion, and Numerator across a 5-patient cohort.

Each lesson checks your CQL define-by-define against expected results, lets you inspect the underlying patient data, drill into failed checks to see which resources a define reads, and compare your work with the reference solution.