OBJECTIVES

Japan’s National Health Insurance (NHI) has a nationwide list of drugs covered. A new reimbursement for the introduction of a formulary has been examined. However, nobody knows how much of the reimbursement would be appropriate, or even whether the introduction would reduce the National Health Expenditure (NHE) or not. This research would help the government’s decision on the reimbursement by simulating a hypothetical change of the cost of Oral Antidiabetic Drugs (OADs) if the formularies were introduced.

METHODS

: We analyzed an anonymously processed health insurance claims database of National Health Insurance provided by DeSC Healthcare. National Health Insurance is a type of NHI. The insurers are municipalities, and the insureds include self-employed and retirees. OAD claims in 2019 are identified by “A10” of the first 3 digits of ATC code associated to each drug claim. We calculated the cost per member per month (PMPM) of OADs, and simulated the PMPM if a formulary were introduced. Two formularies, one provided by UnitedHealth and the other by Kaiser Permanente for commercial HMO, were applied.

RESULTS

: The number of insureds was 88,223. The average age and the percent of females are 51.7 and 50.0％ respectively. The number of insureds having at least one OAD claims in 2019 and their average age and percent of females were 7,071, 65.8 and 36.1％ respectively. The current PMPM of OADs was $4.13, among which $1.28 was for OADs within the UnitedHealth’s formulary. If all current OADs were replaced by the OADs within UnitedHealths’s formulary, the PMPM of OADs would be $2.68. If they were replaced by the OADs within Kaiser’s formulary, that would be $2.15.

CONCLUSIONS

: The introduction of formularies to OADs would reduce the PMPM of OADs from $4.13 to $2.68 or $2.15, which are equivalent of the reduction of NHE by $2-3 billion.