[Clinical trials with drugs: the influence of the authorization process].
BACKGROUND: The prevailing regulations require previous review and approval by the administrative authority for clinical trials with drugs in Spain. These regulations have led to the development of a data base of clinical trials submitted for authorization by the Ministry of Health and Welfare. The influence of the evaluation process of authorized clinical trials and the final quality of these trials were studied through this data base. METHODS: The following data corresponding to 1989 and 1990 and grouped in 9 aspects were collected: clarifications applied to protocols of clinical trials, modifications carried out and the causes motivating refusal. Likewise were analyzed the evaluation of quality of each of the aspects considered and the methodological characteristics of the authorized trials. RESULTS: In 1989 and 1990, 298 and 349 protocols of clinical trials were presented; clarifications were requested to 72% in 1989 and to 55% in 1990 (p = 0.0001). Sixty-eight percent and 83% of the trials, respectively were authorized and 19% and 4% were refused and 20% and 13% were annulled, respectively (p = 0.0001). Out of the authorized protocols, 139 (69%) and 144 (50%) received approval following the introduction of modifications (p = 0.0001); of the authorized clinical trials which received clarifications, 94% and 95%, respectively were modified. Among the causes for refusal of the trial 54% and 29% were refused for considering that the trial would not provide relevant information, 58% and 71% for design aspects and 37% and 14% for inadequate patient selection. Of the authorized clinical trials 83% were controlled and randomized in both years with 76% and 73% being blind. CONCLUSIONS: Administrative intervention positively influences in the methodologic and ethical aspects of a relevant part of the authorized clinical trials. The final quality of the clinical trial protocols appears to be comparable to the quality observed by other authors in the clinical trials published in the international literature.