Background: Financial payments from the drug industry to U.S. physicians are common. Payments may influence physicians' clinical decision making and drug prescribing.
Purpose: To evaluate whether receipt of payments from the drug industry is associated with physician prescribing practices.
Data sources: MEDLINE (Ovid), Embase, the Cochrane Library, Web of Science, and EconLit were searched without language restrictions. The search had no limiting start date and concluded on 16 September 2020.
Study selection: Studies that estimated the association between receipt of industry payments (exposure) and prescribing (outcome).
Data extraction: Pairs of reviewers extracted the primary analysis or analyses from each study and evaluated risk of bias (ROB).
Data synthesis: Thirty-six studies comprising 101 analyses were included. Most studies (n = 30) identified a positive association between payments and prescribing in all analyses; the remainder (n = 6) had a mix of positive and null findings. No study had only null findings. Of 101 individual analyses, 89 identified a positive association. Payments were associated with increased prescribing of the paying company's drug, increased prescribing costs, and increased prescribing of branded drugs. Nine studies assessed and found evidence of a temporal association; 25 assessed and found evidence of a dose-response relationship.
Limitation: The design was observational, 21 of 36 studies had serious ROB, and publication bias was possible.
Conclusion: The association between industry payments and physician prescribing was consistent across all studies that have evaluated this association. Findings regarding a temporal association and dose-response suggest a causal relationship.
Primary funding source: National Cancer Institute.