Purpose: Clinical research is widely sponsored by drug and device companies. We investigated whether industry sponsored drug and device studies have more favorable outcomes and differ in risk of bias, compared with studies having other sources of sponsorship. This review is an update of a previous Cochrane review.
Methods: In this update we searched MEDLINE and Embase (2010 to February 2015), Cochrane Methodology Register (2015, Issue 2) and Web of Science (June 2015). We included empirical studies that quantitatively compared primary research studies of drugs or medical devices sponsored by industry with studies with other sources of sponsorship. Two assessors included papers, extracted data and assessed risk of bias. Outcomes included favorable results, favorable conclusions, effect size, risk of bias and whether conclusions agreed with results.
Results: We included 27 additional papers in this update (review now includes 75 papers). Industry sponsored studies more often had favorable efficacy results, RR: 1.27 (95% CI 1.17-1.37), no difference in harms results RR: 1.37 (95% CI 0.64-2.93) and more often favorable conclusions RR: 1.34 (95% CI 1.19-1.51) compared with non-industry sponsored studies. Nineteen papers reported on sponsorship and efficacy effect size, but could not be pooled due to differences in reporting of data and heterogeneity of results. Comparing industry and non-industry sponsored studies, we did not find a difference in risk of bias from sequence generation, allocation concealment, follow-up and selective outcome reporting. However, industry sponsored studies more often had low risk of bias from blinding, RR: 1.25 (95% CI 1.05-1.50), compared with non-industry sponsored studies.
Conclusions: Drug and device studies sponsored by manufacturing companies have more favorable efficacy results and conclusions than studies sponsored by other sources.
Keywords: Bias; Clinical trials; Conflicts of interest; Industry sponsorship; Methodological quality; Outcomes.