Normal-weight obesity and clinical outcomes in nondiabetic chronic kidney disease patients: a cohort study

Normal-weight obesity (NWO), defined by a normal body mass index (BMI) and high body fat percentage, has been shown to be associated with cardiometabolic dysfunction and an increased risk of cardiovascular disease and mortality in the general population. However, little is known about the clinical implications of NWO among patients with chronic kidney disease (CKD). The aim of this study was to assess the characteristics and outcomes of nondiabetic CKD patients with NWO. A total of 178 nondiabetic patients with stages 3-5 CKD were prospectively followed for a median of 4.9 y. The patients were classified into 3 different adiposity phenotypes: nonobese [BMI (in kg/m(2)) < 25 and fat mass percentage (FM%) a parts per thousand 25% for men or a parts per thousand 35% for women], NWO (BMI < 25 and FM% > 25% for men or > 35% for women), and preobese-obese (BMI a parts per thousand 25). FM% was determined using the Body Composition Monitor, a multifrequency bioimpedance spectroscopy device. The outcome was a composite of cardiovascular events or all-cause mortality. The prevalence of NWO was 28.1% among nondiabetic CKD patients with a normal BMI. NWO patients were older, had lower lean body mass, and had higher plasma interleukin-6 concentrations than nonobese patients. However, homeostatic model assessment for insulin resistance levels did not differ between the 2 groups. NWO patients showed a significant 3-fold higher risk of the composite outcome (HR 2.96, 95% CI: 1.13, 7.77; P < 0.05) than did nonobese patients in the fully adjusted model. Preobese-obese patients were not at increased risk compared to nonobese patients. NWO was associated with the worst prognosis among the 3 different adiposity phenotypes in nondiabetic CKD patients. Our findings suggest the importance of using direct measures of adiposity for risk assessment in CKD patients who are normal-weight. This trial was registered at clinicaltrials.gov as NCT03285074.