How to Read a Clinical Trial Registry Entry
Registry records reveal what a trial promised to measure before it began — which is how you detect a moved goalpost.
Last reviewed September 10, 2026
Public trial registries record a study's design, population, endpoints and status before enrolment. Comparing the registered plan with the published paper is one of the most powerful appraisal techniques available to a non-specialist.
Fields worth checking first
Primary outcome measure: the endpoint the trial was designed and powered to answer. Enrolment: whether the actual number matched the plan. Status: whether the trial completed, was terminated, or withdrew — and whether a reason was given.
Phase tells you the purpose. Phase 1 is about safety and dose; phase 2 about preliminary effect; phase 3 about confirmation in the intended population.
Outcome switching
If a paper's headline result is not the registered primary outcome, that is a material finding about the paper. It does not automatically invalidate it, but the analysis should be read as exploratory.
A registered trial with no results posted years after completion is also informative. Absence of publication is not neutral.