Impact of changes in metabolic health and obesity on incident urolithiasis: A nationwide cohort study.

PURPOSE: To evaluate whether time-varying changes in metabolic health and obesity status are associated with incident urolithiasis using a nationwide health-screening cohort. MATERIALS AND METHODS: The National Health Insurance Service-National Health Screening database was used for this study. The study cohort consisted of 514,866 health screening examinees between 2009 and 2010. Metabolic health was determined based on triglyceride, high-density lipoprotein cholesterol, fasting glucose, blood pressure, and waist circumference criteria, while obesity was determined by body mass index. The participants were stratified into metabolically healthy non-obese (MHNO); metabolically unhealthy non-obese (MUNO); metabolically healthy obese (MHO); metabolically unhealthy obese (MUO). According to the second health screening, each group was divided according to changes in metabolic status and obesity. Cox proportional hazards regression was used to determine adjusted hazard ratios (aHRs) and 95% confidence intervals. RESULTS: A total of 286,175 examinees who contributed 1,958,405 person-years of follow-up were eligible for this cohort study, during which 12,403 subjects developed urolithiasis. Compared with MHNO individuals, aHRs for incident urolithiasis were higher in MUO, MHO, and MUNO groups. Persistent obesity or metabolic unhealthiness was associated with higher aHRs, whereas improvement in either status was associated with lower aHRs. CONCLUSIONS: We found that aHRs for incident urolithiasis were similarly elevated in metabolically healthy and unhealthy obese individuals compared with MHNO individuals, indicating that excess adiposity may be a key driver of stone risk. Maintaining metabolic health and normal weight or improving metabolic health and reducing weight may lead to decreased risk of urolithiasis development.