Factors of geographical variability of antimicrobial use in Japan

Abstract

Abstract Background The evidence regarding the factors affecting the geographical variation of antimicrobial use (AMU) is relatively scarce. The study aimed to evaluate factors potentially associated with geographical variability of AMU per day per 1,000 habitants in 47 prefectures of Japan. Methods This is an observational ecological study using the Japanese national database in 2019. The outcome was the defined daily doses per 1,000 inhabitants per day by prefecture. The multivariable negative binomial regression analysis was conducted using patient- and physician-level variables. Results The study included 605,391,054 defined daily doses of AMU in 2019 from the 47 prefectures. In the multivariable negative binomial regression analyses for the outcome of total AMU, the proportion of females (RR 1.04 [1.01 − 1.08] per 1% increase, p = 0.021), the proportion of upper secondary graduates going to further education (RR 1.01 [1.00 − 1.01] per 1% increase, p = 0.005) and the annual number of diagnoses related with upper respiratory infections (URIs) per 1,000 inhabitants per day (RR 1.21 [1.10 − 1.34], p < 0.001) were significantly correlated with total AMU. Conclusions In the ecological study, the variability of total AMU by Japanese prefecture was associated with the proportion of females, the education level and the number of URI diagnoses per population. The results suggest the potential need for additional stewardship efforts to reduce unnecessary antimicrobial prescriptions for URI.