Nature and Trend of Pharmaceutical Payments to Japanese Board-Certified Neurologists Between 2016 and 2019: A Pre-emergence Analysis Amidst the Development of Next-Generation Alzheimer's Disease Drugs

Objective: There is insufficient data on the financial relationships between Japanese neurologists and pharmaceutical companies prior to the advent of new -generation Alzheimer's disease drugs. The purpose of this study is to evaluate the magnitude, prevalence, and trend of the financial relationship between Japanese neurologists and pharmaceutical companies between 2016 and 2019. Methods: A cross-sectional study was undertaken to evaluate the financial relationships between all boardcertified neurology specialists and pharmaceutical companies in Japan from 2016 and 2019. Descriptive statistics were applied to measure the magnitude and prevalence of payments among specialists, as well as their trends during the study periods. Results: In a four-year analysis, 77 pharmaceutical companies disbursed a total of USD 36,869,204 across 50,050 payments to 2,696 neurologists in Japan, revealing a mean payment of USD 10,809 per specialist. Notably, the Gini index of 0.997 indicated a high inequality in payment distribution, with a minority of specialists receiving a substantial proportion of payments. Trends displayed irregularities, but an overall increase in total payments from 2016 to 2019, with a significant contribution from the top 10 pharmaceutical companies accounting for 74.2% of total payments, with Takeda Pharmaceutical and Eisai Company notably increasing payments in 2019. There were notable geographical variations in neurologist and payment distribution across 47 prefectures. Conclusion: Our analysis of neurologist payments from pharmaceutical companies in Japan showed a substantial financial relationship with overall increases, yearly varied increments, and payment inequality. Caution is warranted as financial ties may intensify with the continued development of next -generation Alzheimer's disease drugs.