Informed consent in European multicentre randomised clinical trials--are patients really informed?

This study was designed to examine the standard of consent used by investigators in European randomised clinical trials (RCT). The participants of 12 multicentre RCTs published in the European Journal of Cancer in the years 1990-1992 were asked to complete a short questionnaire regarding their practice of obtaining consent in the trial reported. Anonymity was assured. Replies were received from 60 of 88 clinicians contacted. Data showed that 12% of clinicians did not inform their patients about the trial prior to randomisation. Thirty-eight per cent of clinicians did not always tell patients that they had been assigned to their treatment randomly. Only 32% of clinicians used written consent, 21% used written information without obligatory signing, 42% used verbal consent, and in 5% no consent was sought. Even when information was given, only 58% of clinicians gave full information on all aspects of the trial and 42% gave information on the proposed treatment arm only (27% revealing inclusion in an RCT). When examined by geographical origin, clinicians in northern Europe were more likely to obtain full consent than those from southern Europe. Similarly, the level of consent was higher in trials of supportive care than in trials testing curative or palliative antitumour therapies.