Promoting generic drug usage in Japan: correlation between generic drug usage and monthly personal income

Abstract

Background To reduce pharmacy-related medical expenses, it is necessary to cut drug costs, potentially by increasing generic drug usage. This study analyzes the correlation between generic drug usage and monthly personal income by examining prescriptions for individual drugs. Methods We conducted a cross-sectional study based on the data set from the National Database of Health Insurance Claims and Specific Health Checkups of Japan Open Data Japan and the Basic Survey on Wage Structure. We calculated the correlation coefficient between the usage rate of generic drugs in each prefecture of Japan and monthly personal incomes. We then analyzed the correlation coefficients based on the therapeutic categories of medicinal drugs; the contingency table was visualized as a mosaic plot. To compare the proportions between multiple categories, the chi-squared test was applied as a statistical significance test that was used in the analysis of n × m contingency tables. We worked with the null hypothesis that there were no differences between classes in the population. Results Regarding the correlation coefficient between the usage rate of generic drugs and monthly personal incomes, the proportion of negative correlation coefficients for outpatient out-of-hospital and outpatient in-hospital prescriptions was over 70%, while that for inpatient prescriptions was 46.9%. The proportion of medicinal drugs exhibiting a negative correlation between the rates of generic drug usage and monthly personal incomes for outpatient out-of-hospital prescriptions and outpatient in-hospital prescriptions was higher than that of inpatient prescriptions. The proportion of statistically correlated medicinal drugs among inpatient prescriptions was lower than that among outpatient out-of-hospital and outpatient in-hospital prescriptions. The proportions of significant negative correlations for outpatient out-of-hospital, outpatient in-hospital, and inpatient prescriptions were 30.6%, 22.7%, and 3.5%, respectively. It was also observed that the rate of generic prescription usage for outpatient out-of-hospital and in-hospital prescriptions increased as monthly personal incomes decreased. In outpatients, the therapeutic categories with strong negative correlations were vasodilators and hyperlipidemia drugs. Conclusions Our results may help to increase the usage rate of generic drugs in different prefectures by providing useful information for promoting them throughout Japan.

Clinical Utilization of Generic Drugs and Biosimilars for Ulcerative Colitis Treatment: Insights from a Nationwide Database Study in Japan

“…In 2020, there were generic drug shortages in Japan owing to manufacturing violence and quality problems caused by several generic pharmaceutical companies [7]. Other factors including the supply-and-demand balance, shortage of ingredients, and management decisions could also contribute to an unstable supply or shortage of generics and biosimilars [26]. Such unstable supply and shortage could cause anxiety in physicians and patients, resulting in the loss of confidence in generics and biosimilars.…”

Study of Factors to Increase the Usage Rate of Generic Drugs in Platelet Aggregation Inhibitors

“…The results of the present study show that the use of generics for drugs with high drug prices is negatively correlated with monthly personal income for both outpatient out-of-hospital and outpatient in-hospital prescriptions. Suzuki et al 32 reported that the proportion of negative correlation coefficients between the usage rate of generic drugs and monthly personal incomes for outpatient out-of-hospital and outpatient in-hospital prescriptions was over 70%, while that for inpatient prescriptions was 46.9%.…”

Survey of community and hospital pharmacist involvement in outpatient chemotherapy using Japanese health information data

“…The NODJ includes basic summary tables created from medical inpatient claims, medical outpatient claims, diagnosis procedure combination (DPC) claims, dispensing claims, dental inpatient claims, dental outpatient claims, and specific health checkups (Ministry of Health, Labour and Welfare, 2022b ). The NODJ has been used in several studies to identify trends in drugs prescribed by the Japanese insurance system (Mukai et al, 2020 ; Suzuki et al, 2023 ; Tanaka et al, 2022 ; Tanito, 2022 ). Furthermore, Japan enacted the Cancer Registration Promotion Act in 2013, where the registration of diagnosed cancer cases was started in 2016 under the new National Cancer Registry (NCR) system (Ministry of Health.…”