The art of choosing sound study endpoints

The selection of appropriate endpoints is the key to successful clinical studies. The chosen primary outcome measure ultimately determines the required sample size, significantly affects trial logistics, and establishes acceptance of results in the scientific community. Confirmatory statistics may only be conducted on the primary endpoint, while secondary endpoints are better analysed in an exploratory fashion. While investigators may prefer surrogates (e.g., radiographic results, laboratory markers) clinical trials should no longer be planned without addressing function or quality of life. Valid outcome tools (e.g., Short-Form 36) are needed to ensure comparability of findings to other studies.