Body Mass Index and Kidney Disease‐Related Mortality in Midlife: A Nationwide Cohort of 2.3 Million Adolescents

OBJECTIVE: This study aimed to evaluate the association of body mass index (BMI) in adolescence with mortality attributed to kidney disease. METHODS: In this study, 2,294,139 Jewish Israeli adolescents with measured weight and height at 17 years old during the military fitness assessment were analyzed with a follow-up extending up to 45 years. All kidney-related outcomes, coded by the Central Bureau of Statistics from death notifications as the underlying cause of death, were obtained by linkage. Cox hazards models were applied. RESULTS: During 42,297,007 person-years of follow-up (median 18.4 years), 226 deaths related to kidney disease were recorded. There was an increased risk for kidney-related death among adolescents with overweight and obesity with adjusted hazard ratios of 2.7 (95% CI: 1.8-3.9) and 8.4 (5.1-13.8), respectively, with BMI between 18.5 and 22.0 kg/m2 as the reference. A 15% increased risk for kidney-related mortality (1.11-1.19) per unit increment in BMI was observed. Furthermore, a multivariable spline model indicated a minimum risk for kidney-related mortality starting at BMI of 18.6 kg/m2 with significantly increased risk seen above values of 22.8 kg/m2 . The results withstood extensive sensitivity analyses, including stratification of kidney-related death attributed to acute, chronic, and total kidney disease. CONCLUSIONS: Adolescent overweight and obesity are risk markers for kidney-related mortality over 4 decades.