Pre-specification of endpoints is a fundamental principle when designing and reporting randomised trials. The registration of randomised trials in clinicaltrials.gov enables an evaluation of whether reported endpoints are pre-specified or have been changed.

Ramagopalan et al. performed a cross-sectional analysis of all interventional clinical trials registered on ClinicalTrials.gov as of 25 October 2012. The analysis showed that 28229 of 89204 (32%) registered studies had their primary outcome changed. The authors also found that industry funding was associated with a higher degree of endpoint changes of the primary outcome than public funding.

The authors conclude that a significant proportion of the trials registered at clinicaltrials.gov have their primary outcomes changed and that the changes are associated with the funding source.

Reference

  1. Ramagopalan S, Skingsley AP, Handunnetthi L, Klingel M, Magnus D, Pakpoor J, Goldacre B. Prevalence of primary outcome changes in clinical trials registered on ClinicalTrials.gov: a cross-sectional study. F1000Research 2014,3:77.