Industry-funded positive studies not associated with better design or larger size.

Previous studies have associated commercial funding with positive outcomes in orthopaedic research. Those reports, however, failed to account for potential confounding variables that can lead to a disproportion of positive outcomes, including sample size, study design, and study quality. We tested the hypothesis that nonscientific factors (funding source, orthopaedic subspecialty, and geographic region of origin) are associated with positive study outcomes, but not the result of differences in study design, study quality, or sample size. All 747 abstracts presented at the 2004 American Academy of Orthopaedic Surgeons annual meeting underwent blinded analysis using previously published criteria. Studies that received commercial funding were more likely to conclude with positive outcomes. Subspecialty and country of origin were not associated with positive outcomes. Commercially funded studies were not more likely than non-funded studies to be well-designed. When control groups were used, those in commercially funded studies were not larger than those used in nonfunded studies. Our data suggest commercial funding was associated with positive outcomes, but we found no evidence to suggest commercially funded studies were better designed or larger than non-funded studies.