Body Mass Index in Late Adolescence and Later Life Kidney Outcomes: A Population-Based Cohort Study in Swedish Men.

Rationale & Objective: The association between body mass index (BMI) and chronic kidney disease (CKD) is well established in middle-aged and older adults. Here, we assess the association of BMI in late adolescence with CKD, kidney failure, and acute kidney injury (AKI) later in life. Study Design Setting & Participants: Population-based cohort study including data from the Swedish Conscription Database, the National Patient Register, the Cause of Death Register, and Statistics Sweden. Conscripts with no history of diabetes, cardiovascular, kidney, or rheumatic diseases enlisted between 1969 and 1997 were followed until December 31, 2019. Main Outcomes & Exposures: The study examined the impact of BMI on kidney outcomes. The primary outcome was incident chronic kidney disease. Secondary outcomes were stage 5 chronic kidney disease, end-stage kidney disease, and acute kidney injury. Analytical Approach: Patients were stratified into the quintiles of BMI at conscription, and followed until events, death, or censoring, using Cox proportional hazards model, adjusted for baseline systolic and diastolic blood pressure, proteinuria, and socioeconomic factors. Results: In total, 1,321,481 male participants with a mean age of 18.3 years and a mean BMI of 21.6 kg/m Limitations: A retrospective observational study of male Swedish adolescents. Conclusions: The findings of this study indicate that, for prevention of kidney disease, the optimal BMI in adolescence with reference to kidney outcomes is likely in the low-normal range.