Impact of reimbursement restriction on drug market sales under the National Health Insurance in Japan.

Aim: National health care expenditures have been increasing each year, although the Japanese government has annually revised official drug prices. Managing the health care system to pay for expensive drugs is a major concern. The reimbursement restriction, which is the only way that a drug can be implemented before market entry in Japan, is crucial for managing expenditures. Therefore, this study identifies the impact of the reimbursement restriction on drug market sales in Japan, particularly in the situation where health technology assessment or other market access regulations are not applicable before market entry.
Method: All new drugs listed in fiscal years 2011-2019, along with their market size forecast, were identified using the materials from the Central Social Insurance Medical Council. We then calculated the percentage rate of reimbursement amounts based on the National Database of Health Insurance Claims relative to the predicted market size as a dependent variable. Using the reimbursement restriction for each drug as an independent variable, we performed descriptive and univariate analyses on each variable, followed by generalized linear mixed-effects model regression analysis.
Results: We identified 211 drugs. The mean rates of drugs that required physicians, facilities, and patients to meet criteria for use were 30.85% ( n  = 2), 31.42% ( n  = 2), and 72.11% ( n  = 6), respectively. The mean rate of drugs that required diagnostic testing was 22.99% ( n  = 7), which was 3.7 times lower than the rate of drugs that did not require such testing ( p  < .05).
Conclusion: Our results indicate that the reimbursement restriction requiring diagnostic testing has a substantial impact on decreasing market sales. As the number of cases for each requirement is small, further study is needed to measure the impact of the other reimbursement restrictions.