Crocetti and colleagues used the Cochrane Collaboration tool, which assesses risk for bias along six critical aspects including randomization randomly assigning patients to different treatments and masking, the degree to which neither the patient nor the doctor knows which group of patients is receiving an active drug or intervention versus a placebo.
Investigators say that by analyzing each clinical trial along these and four other dimensions, the Cochrane Collaboration can answer what are perhaps the most important questions in medical research: How strong is the causal relationship between the therapy and the effect? and How valid are the conclusions made about the effect of the therapy?
Overall, 41 percent of the 146 trials in the review had improper or poorly described randomization techniques. Industry-funded trials were six times more likely to have high risk for biased randomization than government-funded trials or those funded by nonprofit organizations. And past research, the investigators point out, has shown that industry-funded trials are four to five times more likely to recommend an experimental drug.
"Industry funding is an important driver of medical discovery, but it is critical for investigators involved in such trials to ensure not only that the studies are conceived and executed cautiously with minimum risk for bias, but that any precautions taken against bias are also reported transparently," Crocetti says.
Trial registration and the transparency commitment it reflects is a key step in reducing bias or its influence, the researchers say. In their evaluation, registered trials were nearly 70 percent more likely to have robust randomization than non-registered trials, probably because the registration process itself forces researchers to answer many questions rel
|Contact: Ekaterina Pesheva|
Johns Hopkins Medical Institutions