Deliberate concealment of unfavorable clinical trial results from regulators and the public
Clinical trial suppression refers to the deliberate concealment, manipulation, or selective reporting of clinical trial data to hide unfavorable results about a pharmaceutical product's safety or efficacy. This practice distorts the scientific record, misleads prescribers and patients, and can result in widespread harm from drugs whose true risk profiles have been concealed.
The practice takes multiple forms. Publication bias means that trials with positive results are far more likely to be published than trials with negative results. Selective outcome reporting involves publishing only the favorable endpoints from a trial while omitting unfavorable ones. Data manipulation can include excluding participants who experienced adverse events, changing primary endpoints mid-trial, or using statistical techniques that obscure negative signals.
Documented cases are extensive. GlaxoSmithKline suppressed data showing its antidepressant Paxil increased suicidal thinking in adolescents. Merck concealed cardiovascular risks associated with Vioxx. Studies of antidepressant efficacy found that when unpublished trial data was included alongside published data, the apparent benefits were dramatically reduced. The AllTrials campaign and ClinicalTrials.gov registration requirements were created specifically to combat trial suppression, but compliance remains incomplete.
