Lower thigh muscle mass is associated with all-cause and cardiovascular mortality in elderly hemodialysis patients

BACKGROUND/OBJECTIVES: Higher body mass index appears protective in hemodialysis patients, although it remains to be determined which component of muscle or fat mass is primarily associated with this survival advantage. SUBJECTS/METHODS: Eighty-one hemodialysis patients in our institution were prospectively followed from July 2011 to August 2015. Muscle and fat mass were evaluated by measuring the cross-sectional areas of the thigh and abdomen using computed tomography. The relationship between muscle and fat mass, and all-cause and cardiovascular mortality was studied using the Kaplan-Meier analyses and multivariate Cox proportional hazard models. RESULTS: During more than 4 years of follow-up, 26 patients (32%) died. In the Kaplan-Meier curve analyses, lower thigh muscle mass was significantly associated with all-cause and cardiovascular mortality (log-rank test, P < 0.01 and P < 0.001, respectively), but there was no such association with thigh fat, abdominal muscle and fat mass levels. In multivariate Cox proportional hazard models, each 0.1 cm(2)/kg increase in the thigh muscle area adjusted by dry weight was associated with an estimated 22% lower risk of all-cause mortality (95% confidence interval (95% CI), 0.64- 0.95, P < 0.05) and a 30% lower risk of cardiovascular mortality (95% CI, 0.54-0.90, P < 0.01). CONCLUSIONS: Lower thigh muscle mass is significantly associated with all-cause and cardiovascular mortality in hemodialysis patients. Our findings indicate the importance of focusing on the muscle mass of lower extremities to predict the clinical outcomes of hemodialysis patients.