Impact of transition in metabolic health and obesity on the incident chronic kidney disease: A nationwide cohort study

CONTEXT: Metabolically healthy obesity (MHO) is a dynamic condition. OBJECTIVE: To evaluate the risk of chronic kidney disease (CKD) among people with MHO according to its longitudinal change. DESIGN: Observational study. SETTING: A nationwide population-based cohort. PARTICIPANTS: A total of 514 866 people from the Korean National Health Insurance Service-National Sample Cohort. INTERVENTION: The initial presence and changes of obesity (using body mass index [BMI] and waist circumference [WC]) and metabolic health status. MAIN OUTCOME MEASURE: Incident CKD from 2011 to 2015. RESULTS: Of the people classified as MHO at baseline (BMI criteria), 47.6% remained as MHO in 2011 and 2012, whereas 12.1%, 5.5%, and 34.8% were classified as metabolically healthy, non-obese (MHNO), metabolically unhealthy, non-obese, and metabolically unhealthy, obese, respectively. The risk of incident CKD in the baseline MHO group was higher than that in the MHNO group (hazard ratio, 1.23; 95% confidence interval, 1.12-1.36). However, when transition was taken into account, people who converted to MHNO were not at increased risk (hazard ratio, 0.98; 95% confidence interval, 0.72-1.32), whereas the stable MHO group and the groups that evolved to metabolically unhealthy status had a higher risk of incident CKD than the stable MHNO group. When the risk was analyzed using WC criteria, it showed a similar pattern to BMI criteria except for the stable MHO group. CONCLUSIONS: MHO was a dynamic condition, and people with MHO constituted a heterogeneous group. Although the MHO phenotype was generally associated with incident CKD, maintenance of metabolic health and weight reduction might alleviate the risk of CKD.