EMA: Scientific guideline: Guideline on missing data in confirmatory clinical trials
This guideline provides advice on how the presence of missing data in confirmatory clinical trials should be addressed and reported in a dossier submitted for regulatory review and provides an insight into the regulatory standards that will be used to assess confirmatory clinical trials with missing data. The main focus of this guideline is issues associated with the analysis of the primary efficacy endpoint where patients are followed up over time. Typically in such trials, some patients withdraw from the study or are lost to follow-up and hence data for those patients are missing from some point at or after a baseline assessment through to the end of the study. The principles outlined apply to superiority and non-inferiority trials as well as to equivalence trials, though the same biased estimate of the treatment effect may lead to different conclusions for trials with different objectives.