Failure to Accept the Results of Randomised Controlled Trials

Abstract

The result of a trial may not be accepted for several reasons: the result may be at variance with preconceived ideas; an unusual group of patients may have been recruited; the treatment groups may not be identical in important respects; too few patients may have been recruited and the power of the trial may be too low; the results of the trial may not have been interpreted correctly; the trial result may not be consistent across different strata of patients; the trial may provide a result that conflicts with the results of other trials; the treatment may be difficult to administer or have too many adverse effects; and finally, the trial may originate from a group with a vested interest in demonstrating the observed result (for example, a pharmaceutical company). Before discussing each of these reasons we shall illustrate them by describing three trials whose results have not been completely accepted and also three series of trials on related drugs, the collective results of which are difficult to interpret. After discussing these trials, we shall return to the reasons for rejecting the results of a randomised controlled trial.