The Dose-Response Relationship Between Body Mass Index and the Risk of Incident Stage ≥3 Chronic Kidney Disease in a General Japanese Population: The Ibaraki Prefectural Health Study (IPHS)

PURPOSE To examine the relationship between body mass index (BMI) and the risk of stage ≥3 chronic kidney disease (CKD) in a general Japanese population. METHODS A total of 105 611 participants aged 40-79 years who completed health checkups in Ibaraki Prefecture, Japan, and were free of CKD in 1993 were followed-up through 2006. Stage ≥3 CKD was defined by an estimated glomerular filtration rate <60 mL/min/1.73 m(2) reported during at least 2 successive annual surveys or as treatment for kidney disease. Hazard ratios (HRs) for the development of stage ≥3 CKD relative to the BMI categories were calculated using the Cox proportional hazards regression model, which was adjusted for possible confounders and mediators. RESULTS During a mean follow-up of 5 years, 19 384 participants (18.4%) developed stage ≥3 CKD. Compared to a BMI of 21.0-22.9 kg/m(2), elevated multivariable-adjusted HRs were observed among men with a BMI ≥23.0 kg/m(2) and women with a BMI ≥27.0 kg/m(2). Significant dose-response relationships between BMI and the incidence of stage ≥3 CKD were observed in both sexes (P for trend <0.001). CONCLUSIONS Obesity was associated with the risk of developing stage ≥3 CKD among men and women.