Incremental Effect of Aging on Obesity-Related Incident Chronic Kidney Disease in the Korean General Population.

OBJECTIVES Obesity may increase the risk of kidney function decline. However, few studies have addressed how age modifies obesity-associated risk of chronic kidney disease (CKD) in the Asian general population. DESIGN A community-based prospective cohort study. SETTING AND PARTICIPANTS 6538 Korean general population with normal kidney function from the Korean Genome and Epidemiology Study Database. METHODS Participants were stratified according to age (40-49, 50-59, and 60-69 years old) and body mass index [≥18.5-<23 (normal-weight), ≥23-<27.5 (overweight), and ≥27.5 (obese)]. We conducted Kaplan-Meier and multivariable-adjusted Cox regression analyses to investigate the association of aging and obesity with incident CKD. RESULTS During the 12-year follow-up, an overall incidence rate of CKD was 6.1 cases per 1000 person-years. Obese, but not overweight, people had an increased risk of incident CKD compared with normal-weight people in multivariable models adjusted for metabolic factors. When analyzed by 10-year increments, this association was significant only in 60-69-year-old individuals. Kaplan-Meier analysis showed that the incidence of CKD associated with overweight or obesity showed an accentuated increase with age. With reference to normal-weight individuals aged 40-49 years, the adjusted hazard ratio of CKD increased with age regardless of body mass index, and the positive association between obesity and incident CKD was more prominent with increasing age. CONCLUSIONS AND IMPLICATIONS Obesity-associated risk of incident CKD was accentuated in older people, and this association was independent of metabolic abnormalities.