Who Pays for Gifts to Physicians? Heterogeneous Effects of Industry Payments on Drug Costs

Abstract

This paper estimates the impact of gifts - monetary or in-kind payments - from pharmaceutical firms on physicians' prescription decisions and drug costs in the US. Using exhaustive micro data on prescriptions for anti-diabetic drugs from Medicare Part D, we find that payments cause physicians to prescribe more brand drugs. On average, for every dollar spent, payments generate a $6 increase in drug costs. We then estimate heterogeneous causal effects via machine-learning methods. We find large heterogeneity in responses to payments across physicians. Differences are predominantly explained by the insurance coverage of patients: physicians prescribe more brand drugs in response to payments when patients benefit from subsidies that reduce out-of-pocket drug costs. Finally, we estimate that a gift ban would reduce drug costs to treat diabetes by 3%.