Results from clinical studies on drugs and medical devices affect how doctors practice medicine and thereby the treatments offered to patients. However, clinical research is increasingly sponsored by companies that make these products, either because the companies directly perform the studies, or fully or partially fund them. Previous research has found that pharmaceutical industry sponsored studies tend to favor the sponsors’ drugs much more than studies with any other sources of sponsorship. This suggests that industry sponsored studies are biased in favor of the sponsor’s products.
This review is an update of a previous review on this topic that looked only at drug studies. It uses more rigorous methodology and also investigates sponsorship of medical device studies. The primary aim of the review was to find out whether the published results and overall conclusions of industry sponsored drug and device studies were more likely to favor the sponsors’ products, compared with studies with other sources of sponsorship. The secondary aim was to find out whether such industry sponsored studies used methods that increase the risk of bias, again compared with studies with other sources of sponsorship. We did a comprehensive search of all relevant papers published before September 2010 and included 48 papers in our review.
Industry sponsored drug and device studies more often had favorable efficacy results, (risk ratio (RR): 1.32, 95% confidence interval (CI): 1.21 to 1.44), harms results (RR: 1.87, 95% CI: 1.54 to 2.27) and overall conclusions (RR: 1.31, 95% CI: 1.20 to 1.44), compared with non-industry sponsored drug and device studies. We did not find a difference between industry and non-industry sponsored studies with respect to standard factors that may increase the risk of bias, except for blinding: industry sponsored studies reported satisfactory blinding more often than non-industry sponsored studies. We did not find a difference between drug and device studies on the association between sponsorship and conclusions. In industry sponsored studies, there was less agreement between the results and the conclusions than in non-industry sponsored studies, RR: 0.84 (95% CI: 0.70 to 1.01). Our analysis suggests that industry sponsored drug and device studies are more often favorable to the sponsor’s products than non-industry sponsored drug and device studies due to biases that cannot be explained by standard 'Risk of bias' assessment tools.