Sarcopenic obesity and body composition phenotypes in older adults with chronic kidney disease: associations with estimated mortality risk

Alterations in body composition are highly prevalent in older adults with chronic kidney disease (CKD) and may contribute to adverse health outcomes. In particular, the coexistence of sarcopenia and obesity—referred to as sarcopenic obesity—has emerged as a potentially high-risk nutritional phenotype. However, it remains unclear whether sarcopenia and obesity exert synergistic or merely additive effects on estimated geriatric risk in older adults with CKD. This cross-sectional study included 222 older adults (aged ≥ 70 years) with CKD (defined as estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m2 and/or albuminuria ≥ 30 mg/g) who underwent comprehensive geriatric assessment and multimodal body composition evaluation. Sarcopenia was defined according to EWGSOP2 criteria using muscle strength and muscle mass assessed by bioelectrical impedance analysis and computed tomography. Obesity was defined as body mass index ≥ 30 kg/m2. Participants were classified into four body composition phenotypes: no sarcopenia/no obesity, obesity only, sarcopenia only, and sarcopenic obesity. Estimated 10-year mortality and disability risks were calculated using validated geriatric risk indices. Outcomes represent estimated risk scores rather than observed clinical events. Sarcopenia-related phenotypes were associated with higher estimated mortality risk (p < 0.001) and disability risk (p = 0.046). In multivariable analyses, lower eGFR, lower serum albumin, sarcopenia, and obesity were each independently associated with higher estimated mortality risk, whereas the interaction between sarcopenia and obesity was not significant, suggesting additive rather than synergistic effects. For disability risk, serum albumin was the only independent predictor; sarcopenia was not independently associated with estimated disability risk in the adjusted model. In this cross-sectional study of older adults with CKD, sarcopenia and obesity were independently associated with higher estimated mortality risk scores, with sarcopenia showing a stronger association. These exploratory findings support further evaluation of muscle-centered nutritional assessment beyond BMI in older adults with CKD, though prospective studies with observed clinical outcomes are needed to confirm these associations.