Bias in reporting clinical trials

The primary aim of the present study was to identify possible occurrence of selective reporting of the results of clinical trials to the Finnish National Agency for Medicines. Selective reporting may lead to poorly informed action or inaction by regulatory authorities.

In 1987, 274 clinical drug trials were notified to the Finnish National Agency for Medicines. By December 1993, final reports had been received from 68 of these trials and statements that the trial had been suspended from 24 trials. The sponsors of the non-reported trials were requested to report the outcome. The outcomes, if any, of all reported and non-reported trials were classified as positive, inconclusive or negative.

The total number of trials with positive, inconclusive or negative outcome were 111, 33 and 44, respectively; the outcomes of 86 trials could not be assessed. Final reports were received from 42/111 (38%) trials with positive, 6/33 (18%) with inconclusive and 9/44 (20%) with negative outcomes.

Substantial evidence of selective reporting was detected, since trials with positive outcome resulted more often in submission of final report to regulatory authority than those with inconclusive or negative outcomes.