Level of Evidence and Industry Sponsorship Associated with Favorable Outcomes in Publications on Platelet-Rich-Plasma Therapy in Musculoskeletal Disorders

Platelet-rich plasma is derived from centrifuging whole blood. There is increasing interest in the sports medicine and athlete community about providing endogenous growth factors directly to the injury site, using autologous blood products such as platelet-rich plasma. The aim of the present study is to evaluate the association between research financing, conflict of interests, level of evidence and author affiliation with the interpretation of results in articles published on platelet-rich plasma therapy in musculoskeletal ailments. A review of the current literature was performed. The outcome was classified as favorable or unfavorable. The declaration of conflict of interests and the type of funding was extracted from each article. The financing was classified as industry-sponsored; not industry-sponsored; or unidentifiable. The level of evidence was categorized from I to IV. Higher positive outcomes were observed in 134 studies with industry sponsorship compared with not industry-sponsored studies (odds ratio [OR]: 0.26; 95% confidence interval [95%CI]: 0.08-0.85; p  < 0.05). Compared with level of evidence I, levels II and IV increase the probability of positive outcomes by 12.42 times ( p  < 0.01) and 10.97 times ( p  < 0.01) respectively. Proportionally, industry-sponsored studies are more likely to present positive results, as well as articles with a lower quality of evidence.