Prefecture-specific prevalence of overweight/obesity is associated with regional variation in the incidence of treated ESKD in Japan

BACKGROUND: Overweight/obesity is a significant risk factor for chronic kidney disease and end-stage kidney disease (ESKD) in the general population. This study evaluated the impact of sex- and prefecture-specific prevalence of overweight/obesity on standardized incidence rates (SIRs) of treated ESKD in Japan. METHODS: We conducted an ecological study of all prefectures in Japan (n = 47) using data from the Japanese Society of Dialysis Therapy, national census, the NDB Open Data, and the Statistics of Physicians, Dentists and Pharmacists. We calculated the prevalence of overweight/obesity and proteinuria, standardized mortality ratio, and ratio of nephrology specialists for each prefecture, and explored associations of these variables with sex- and prefecture-specific SIRs of treated ESKD using bivariate association analysis, multiple regression analysis, and structural equation modeling (SEM). RESULTS: Prefecture-specific SIRs ranged from 0.72 to 1.24 for men and 0.69–1.41 for women. Prefecture-specific SIRs were significantly correlated with both the prevalence of overweight/obesity and prevalence of proteinuria. The prevalence of overweight/obesity showed direct, positive, and significant associations with prefecture-specific SIRs in men (standardized estimate (β) = 0.43, p < 0.001) and women (β = 0.40, p < 0.001). The prevalence of proteinuria showed a significant association with prefecture-specific SIRs only in women (β = 0.33, p = 0.01). The SEM models explained 26% of the variance in SIR for men and 28% for women. CONCLUSIONS: Our findings provide evidence that the prefecture-specific prevalence of overweight/obesity in Japan can explain regional variation in prefecture-specific SIRs of treated ESKD in both sexes.