Clinical trials often fail to cite relevant past studies, researchers find

Clinical trials are a pivotal tool for assessing the safety and efficacy of medical interventions, but sponsors often provide incomplete information for assessing their ethical justification. Researchers publishing in the journal Med on April 8 show that many North American clinical trials fail to account for previous or ongoing trials, an omission that could cause researchers to do redundant or less impactful studies.

Using the registry ClinicalTrials.gov, the researchers evaluated 101 randomly chosen clinical trials. Among the ones where there was at least one prior trial testing the same drug in the same disease, 30% of industry-sponsored trials and 20% of non-industry-funded trials neglected to cite related studies. "Clinical trial protocols undercite easily accessible, relevant trials and do not document systematic searches for relevant clinical trials," write the authors.

"Numerous studies suggest that some clinical trials are pursued despite their clinical hypotheses having been resolved prior to study launch," write the authors. "Failure to provide a complete and impartial account of prior and ongoing research in study protocols may enable clinical research that fails to inform clinical practice."