Industry Payments to Physicians and Prescribing Branded Memantine and Donepezil Combination

Zachary A Marcum; Ching-Yuan Chang; Douglas Barthold; Holly M Holmes; Wei-Hsuan Lo-Ciganic

doi:10.1212/CPJ.0000000000000870

Industry Payments to Physicians and Prescribing Branded Memantine and Donepezil Combination

Neurol Clin Pract. 2021 Jun;11(3):181-187. doi: 10.1212/CPJ.0000000000000870.

Authors

Zachary A Marcum¹, Ching-Yuan Chang¹, Douglas Barthold¹, Holly M Holmes¹, Wei-Hsuan Lo-Ciganic¹

Affiliation

¹ Department of Pharmacy (ZAM, DB), University of Washington, Seattle; Department of Pharmaceutical Outcomes and Policy (C-YC, W-HL-C), Center for Drug Evaluation and Safety (C-YC, W-HL-C), College of Pharmacy, University of Florida, Gainesville; and Division of Geriatric and Palliative Medicine (HMH), The University of Texas Health Science Center at Houston, McGovern Medical School.

Abstract

Background: Once-daily extended-released memantine with donepezil (hereafter memantine/donepezil) may improve medication adherence but has a 60-fold higher cost compared with combined generic components. Little is known about factors associated with prescribing memantine/donepezil. We examined the association between pharmaceutical industry payments to physicians and prescribing memantine/donepezil in Medicare.

Methods: A cross-sectional study was conducted. Using 2015-2016 Centers for Medicare and Medicaid Services Open Payments and Part D prescription databases, we identified unique physicians who prescribed ≥11 memantine/donepezil prescriptions from 2015 to 2016. Outcome variable was the number of memantine/donepezil prescriptions written per physician per year. The key independent variable was physician receipt of industry payments defined in 2 models: (1) number of payments and (2) amount of payment ($100 units) for memantine/donepezil received per physician per year. Multivariable Poisson regression was used, adjusting for potential confounders.

Results: Among 4,895 unique eligible physicians in 2015-2016, the median number of memantine/donepezil prescriptions per physician per year was 19.5 (25th percentile 13, 75th percentile 32). Physicians received between 0 and 75 payments per year (median 1, 25th percentile 0, 75th percentile 2.5) for memantine/donepezil, totaling an average of $92 per year (median $10.5, 25th percentile $0, 75th percentile $33.20). Every 1 additional payment received was associated with a 2% increase in new memantine/donepezil prescriptions prescribed per physician per year (rate ratio [RR] 1.02, 95% confidence interval [CI] 1.02-1.02). Every $100 increase in payment for memantine/donepezil was associated with a 0.3% increase in new memantine/donepezil prescriptions prescribed per physician per pear (RR 1.003, 95% CI 1.002-1.004).

Conclusions: Receipt of industry payments for memantine/donepezil was independently associated with increased likelihood of physician prescribing memantine/donepezil in Medicare.