A score system for evaluating random control clinical trials of prophylaxis of abdominal surgical wound infection.

We devised 33 rules for the evaluation of random control trials (RCT) and used them to assess 56 RCTs listed in Index Medicus during 1980-82 on antibiotic prophylaxis of surgical wound infection. We asked 15 questions about design and conduct, 10 about analysis and 8 about presentation. Out of a maximum score of 100 only 16 papers scored over 70, the highest being 89 and the lowest 34. Defects in presentation were not common, and 17 papers scored over 90 per cent. Defects in analysis included the incorrect use of statistical tests and ignoring the Type II error in 'negative' trials; only 13 papers scored over 70 per cent. Defects in design and conduct included transgressions of ethical principles, inappropriate regimens, ill-defined end points and biased randomization or assessment; only 20 papers scored over 70 per cent. We conclude that there is room for improvement in the performance of RCT and that the application of the 33 rules would be helpful not only to researchers but also to editors and referees of scientific journals, and to their readers.