Question
How often do completed interventional Phase 3 trials meet their primary endpoint, and how does the rate vary with therapeutic area, sponsor type, randomisation, blinding, comparator, biomarker-based patient selection, and sample size?
Clinical Evidence Research · CE-1 · Protocol in preparation
Base Rates for Phase 3 Primary Endpoints
How often do registered Phase 3 trials meet their primary endpoint?
Every estimate in CE-2 needs a reference point. A probability for one trial carries information only relative to the rate at which comparable trials succeed. CE-1 builds that reference
Data
Trials registered on ClinicalTrials.gov, retrieved through the registry's public API and the AACT database. Outcomes are matched to posted results and to the primary publication.
Method
Each primary endpoint is classified as met, not met, or unresolved by rules fixed in this protocol. Success rates are estimated per reference class, each with an uncertainty interval. Classification is done twice, independently, and disagreements are recorded.
Limits
Results are not posted for every trial, registry fields are incomplete, and some outcomes can only be resolved from publications. Each limit is quantified in the report.
Output
A reference-class table of Phase 3 success rates. It serves as the base rate against which CE-2 estimates are scored.
Status
Protocol in preparation. Registration date and protocol text are published here before data collection.
References
Wong, C. H., Siah, K. W., Lo, A. W. (2019). Estimation of clinical trial success rates and related parameters. Biostatistics 20(2), 273–286.
BIO, Informa Pharma Intelligence, QLS Advisors (2021). Clinical Development Success Rates and Contributing Factors 2011–2020.