Stopping clinical trials early often exaggerates treatment effects, say Mayo researchers

An international study of nearly 100 clinical trials that were stopped early due to positive treatment effects has found that many of those effects were exaggerated. The authors of the study - published in the current issue of the Journal of the American Medical Association - recommend that researchers resist pressures to end clinical trials early and continue studies for longer periods before even considering premature termination.

'Our research shows that, in most cases, early stopping of clinical trials resulted in misleading estimates of treatment effects. These misleading estimates are likely to result in misguided decisions about the trade-off between risks and benefits of a therapy,' says Victor Montori, Mayo Clinic endocrinologist and corresponding author of the study. 'On average, treatments with no effect would show a reduction in relative risk of almost 30% in stopped early trials. Treatments with a true relative risk reduction of 20% would show a reduction of over 40%,' he noted.