Making Sense of Cohort Definitions, Characterizations, and Generations in OHDSI WebAPI
When I started working with OHDSI WebAPI to build a research data platform, one of the first things that required a genuine shift in thinking was the relationship between cohort definitions, cohort generations, and cohort characterizations. OHDSI separates these into distinct concepts with independent lifecycles — a design that reflects the realities of large-scale observational research: multi-source execution, longitudinal re-runs, and full reproducibility requirements. Once you internalize why the separation exists, the WebAPI endpoint structure starts to feel very intentional. ...