REGIONAL VARIATION IN PRESCRIPTION DRUG USE IN PUBLIC REIMBURSEMENT CLAIMS IN JAPAN: AN ANALYSIS OF NDB OPEN DATA
Author(s)
Kanako Kawada, MSc1, Tomoya Myojin, MD, MEng, PhD2, Yukio Tsugihashi, MD, MPH, PhD3, Tomoaki Imamura, PhD, MD3, Toshiyuki Ojima, MD, PhD2.
1Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan, 2Health Informatics Center; Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan, 3Department of Public Health, Health Management and Policy, Nara Medical University, Kashihara, Japan.
1Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan, 2Health Informatics Center; Department of Community Health and Preventive Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan, 3Department of Public Health, Health Management and Policy, Nara Medical University, Kashihara, Japan.
OBJECTIVES: In Japan, the universal health insurance system covers all residents, and insured people generally pay out-of-pocket costs at fixed coinsurance rates of 10% to 30%. Japan also has public medical care programs, including subsidies for outpatient psychiatric care and medical assistance for low-income households. Understanding prescriptions for vulnerable populations may inform policy, while systematic evidence remains limited. This study aimed to describe prescribing patterns and regional variation in public reimbursement claims.
METHODS: We used the 11th National Database of Health Insurance Claims (NDB) Open Data, aggregate national claims data for services provided in fiscal year 2024. For each oral medication product listed in the NDB Open Data, prescription amount attributable to public reimbursement claims was calculated by subtracting data without public reimbursement claims from data including such claims. We calculated attributable proportions and identified medication products with proportions of 20% or higher. These products were classified by Japanese therapeutic class. Additionally, we calculated the age- and sex-standardized prescription amount ratios by prefecture, setting the national average at 100. Correlations with prefecture-level public assistance rates were examined.
RESULTS: Among oral medications, products with proportions of 20% or higher were concentrated in psychotropic classes. For in-hospital outpatient prescriptions, 176 products (15.22% of products in the class) were classified as psychotropic agents and 27 (7.0%) as hypnotics, sedatives, and anxiolytics. For out-of-hospital outpatient prescriptions, the corresponding numbers were 196 (16.5%) and 40 (10.4%), respectively. Standardized ratios exceeded 100 in 11 prefectures for both therapeutic classes and were strongly positively correlated with public assistance rates for psychotropic agents (Pearson’s r=0.935) and for hypnotics, sedatives, and anxiolytics (r=0.941).
CONCLUSIONS: Notable concentrations of psychotropic medication classes and substantial regional variation were observed in public reimbursement claims. Patient-level analyses are needed to clarify diagnoses, treatment continuity, specific subsidy schemes, and the factors associated with regional variation.
METHODS: We used the 11th National Database of Health Insurance Claims (NDB) Open Data, aggregate national claims data for services provided in fiscal year 2024. For each oral medication product listed in the NDB Open Data, prescription amount attributable to public reimbursement claims was calculated by subtracting data without public reimbursement claims from data including such claims. We calculated attributable proportions and identified medication products with proportions of 20% or higher. These products were classified by Japanese therapeutic class. Additionally, we calculated the age- and sex-standardized prescription amount ratios by prefecture, setting the national average at 100. Correlations with prefecture-level public assistance rates were examined.
RESULTS: Among oral medications, products with proportions of 20% or higher were concentrated in psychotropic classes. For in-hospital outpatient prescriptions, 176 products (15.22% of products in the class) were classified as psychotropic agents and 27 (7.0%) as hypnotics, sedatives, and anxiolytics. For out-of-hospital outpatient prescriptions, the corresponding numbers were 196 (16.5%) and 40 (10.4%), respectively. Standardized ratios exceeded 100 in 11 prefectures for both therapeutic classes and were strongly positively correlated with public assistance rates for psychotropic agents (Pearson’s r=0.935) and for hypnotics, sedatives, and anxiolytics (r=0.941).
CONCLUSIONS: Notable concentrations of psychotropic medication classes and substantial regional variation were observed in public reimbursement claims. Patient-level analyses are needed to clarify diagnoses, treatment continuity, specific subsidy schemes, and the factors associated with regional variation.
Conference/Value in Health Info
2026-11, ISPOR Europe 2026, Vienna, Austria
Value in Health, Volume 29, Issue 12S
Code
HPR174
Topic
Epidemiology & Public Health, Health Policy & Regulatory, Real World Data & Information Systems
Topic Subcategory
Health Disparities & Equity, Insurance Systems & National Health Care
Disease
Mental Health (including addiction), No Additional Disease & Conditions/Specialized Treatment Areas