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Prospective registration of clinical trials is required to safeguard the integrity of human research and help prevent certain kinds of bias or fraud. ClinicalTrials.gov registry allows entries to be edited at any time, creating a trail of historical versions. While changes to a trial protocol are normal, this feature might be used to mask important changes that were made after a study had already started. In this project, we aim to assess the frequency of ‘retroactively prospective’ trial registration, i.e., trials that are registered retrospectively at study start, but whose start date is subsequently changed so that by 5 years post-registration, the start date lies after the first registration date (prospective registration).

We will analyse all ClinicalTrials.gov entries for Completed or Terminated interventional clinical trials first registered in 2015. Historical trial registry entries will be downloaded using a web scraper. Our method might provide journal editors and peer-reviewers with an automated tool to easily uncover potentially questionable reporting practices. 

Our preregistered study protocol can be found on OSF.