Muscle Mass Assessed by Computed Tomography at the Third Lumbar Vertebra Predicts Patient Survival in Chronic Kidney Disease

Abstract

Muscle mass is a key element for the evaluation of nutritional disturbances in patients with chronic kidney disease (CKD). Low muscle mass is associated with increased morbidity and mortality. The assessment of muscle mass by computed tomography at the third lumbar vertebra region (CTMM-L3) is an accurate method not subject to errors from fluctuation in the hydration status. Therefore, we aimed at investigating whether CTMM-L3 was able to predict mortality in nondialyzed CKD 3-5 patients. This is a prospective observational cohort study. We evaluated 223 nondialyzed CKD patients (60.3±10.6years; 64% men; 50% diabetics; glomerular filtration rate 20.7±9.6mLmin1.73m2). Muscle mass was measured by CTMM-L3 using the Slice-O-Matic software and analyzed according to percentile adjusted by gender. Nutritional parameters, laboratory data, and comorbidities were evaluated, and mortality was followed up for 4years. During the study period, 63 patients died, and the main cause of death was cardiovascular disease. Patients who died were older, had lower hemoglobin and albumin, as well as lower muscle markers. CTMM-L3 below the 25th percentile was associated with higher mortality according to the Kaplan-Meier curve (P=.017) and in Cox regression analysis (crude hazard ratio, 1.87 [95% confidence interval, 1.11-3.16]), also when adjusting for potential confounders (hazard ratio 1.83 [95% confidence interval 1.02-3.30]). Low muscle mass measured by computed tomography at the third lumbar vertebra region is an independent predictor of increased mortality in nondialyzed CKD patients.