[The quality of clinical trials published in Spain: an evaluation by an analysis of 3 journals during the 1985-1991 period].

BACKGROUND

The evaluation by readers of a published clinical trial requires that the methodology used in its design and realization be specified in detail. In the present study the quality of clinical trials published in Spain during 1985-1991 has been appraised.

METHODS

This is a revision of all clinical studies published from 1985 to 1991 in the following Spanish medical journals: Medicina Clínica, Revista Clínica Española and Revista Española de Enfermedades Digestivas; the studies were assessed by three persons through the use of a questionnaire (checklist) which contained 15 evaluation sections relative to the methodology used in carrying out a study.

RESULTS

Only an average of 5.5 (+/- 2.8) aspects of the 15 evaluated aspects were considered adequate in the total of clinical trials. Three of the aspects evaluated: "objective of the study", "end point" and "criteria for assessment of outcome" were considered adequate in more than 75% of the cases. Aspects relative to "loss to follow-up", "statistical methods", "analysis of the results", "collection of adverse events", and "approval by an ethical committee" accounted for most methodological defects, being the percentage of studies with correct information below 20%. As to the remaining sections considered, they were found adequate in an intermediate to low percentage (near 30%). There were no differences in quality among the three journals. A slight increase in quality was observed during the last years.

CONCLUSIONS

Major methodological deficiencies appear in the clinical studies published in Spain during the last seven years. The recently approved regulations on clinical trials plus the use of checklists by investigators and journal editors, where detailed ethic and methodological aspects are appraised, can contribute to an increase in quality.