What is already known about this subject: Randomized controlled trials (RCTs) are believed to be one of the best methods of clinical research because they can minimize systematic errors of various types. Temporal trends in the various aspects of RCTs have been studied in several medical fields (e.g. nephrology, hepatology, oncology). However, there is lack of data regarding the trends in the methodological quality of RCTs focusing on antimicrobial agents.
What this study adds: Several important methodological aspects of RCTs on antibacterial agents, such as description of randomization, double blinding, description of the blinding and allocation concealment, have not improved during the last 30 years. AIM To investigate the trends of the methodological quality of randomized controlled trials (RCTs) of antimicrobial agents published during the last 30 years.
Methods: We randomly selected from the Cochrane Central Register of Controlled Trials database 70 RCTs of antibacterial agents that were published during a 30-year study period (1975-2005); specifically, we randomly selected 10 RCTs published during each of the following years: 1975, 1980, 1985, 1990, 1995, 2000 and 2005. In each of the selected RCTs, we searched for information on various methodological aspects and graded the methodological quality of the RCTs to evaluate trends for possible improvement.
Results: No improvement was noted in most of the analysed methodological aspects of the RCTs during the 30-year study period. Description of randomization, double blinding, description of the blinding, and allocation concealment were rather scarce among the evaluated RCTs, without observing a trend for improvement during the study period. We noted improvement in reporting power of the study calculations, baseline data as well as in reporting the presence or not of statistical significance and the statistical cut-off of significance. In only 1/70 RCTs were all 13 of the examined methodological quality aspects met and in one more RCT 12 of them were met.
Conclusions: We did not observe considerable improvement in the quality of the reporting and methodology of RCTs on antibacterial agents during the last 30 years. The methodological quality aspects that need most improvement are those that help safeguard against various types of biases.