Sarcopenia, Obesity, and Mortality in US Adults With and Without Chronic Kidney Disease

Introduction: In predialysis chronic kidney disease (CKD), the association of muscle mass with mortality is poorly defined, and no study has examined outcomes related to the co-occurrence of low muscle mass and excess adiposity (sarcopenic obesity). Methods: We examined abnormalities of muscle and fat mass in adult participants of the National Health and Nutrition Examination Survey 1999-2004. We determined whether associations of body composition with all-cause mortality differed between participants with CKD compared to those without. Results: CKD modified the association of body composition with mortality (P = 0.01 for interaction). In participants without CKD, both sarcopenia and sarcopenic obesity were independently associated with increased mortality compared with normal body composition (hazard ratio [HR] = 1.44, 95% confidence interval [CI] = 1.07-1.93, and HR = 1.64, 95% CI = 1.26-2.13, respectively). These associations were not present among participants with CKD. Conversely, obese persons had the lowest adjusted risk of death, with an increased risk among those with sarcopenia (HR = 1.43, 95% CI = 1.05-1.95) but not sarcopenicobesity (P = 0.003 for interaction by CKD status; HR = 1.21, 95% CI = 0.89-1.65), compared with obesity. Discussion: Sarcopenia associates with increased mortality regardless of estimated glomerular filtration rate, but excess adiposity modifies this association among persons with CKD. Future studies of prognosis and weight loss and exercise interventions in CKD patients should consider muscle mass and adiposity together rather than in isolation.