Association of muscle mass and radiodensity assessed by chest CT with all-cause and cardiovascular mortality in hemodialysis patients

Purpose This study investigates the prognostic value of skeletal muscle index (SMI) and skeletal muscle radiodensity (SMD) measured by chest CT in relation to all-cause and cardiovascular disease (CVD) mortality among hemodialysis (HD) patients. Methods A retrospective study was conducted from January 2015 to December 2021 involving HD patients at a dialysis center. Chest CT scans at the twelfth thoracic vertebra level (T12) were analyzed to assess SMI and SMD. Sex-specific cut-off values for two metrics were determined using maximally selected rank statistics. Hazard ratios (HRs) were calculated to evaluate the associations of SMI and SMD with mortality. The discrimination of prognostic models was also compared. Results The study included 603 patients with a median age of 58 years. Of these, 187 (31.0%) patients with SMI < 30.00 cm(2)/m(2) (male) or < 25.04 cm(2)/m(2) (female) and 192 (31.8%) patients with SMD < 32.25 HU (male) or < 30.64 HU (female) were categorized as lower SMI and SMD, respectively. Over a median follow-up of 3.8 years, 144 deaths occurred. Multivariate Cox regression analysis showed that lower SMI and SMD were independently associated with all-cause mortality (SMI: HR = 1.47, 95% CI 1.03-2.10; SMD: HR = 1.75, 95% CI 1.20-2.54) and CVD mortality (SMI: HR = 1.74, 95% CI 1.03-2.94; SMD: HR = 1.72, 95% CI 1.02-2.95). Adding SMI and SMD to the established risk model improved the C-index from 0.82 to 0.87 (P < 0.001). Decision curve analysis showed that the prognostic model incorporating both SMI and SMD offered the highest net benefit for predicting all-cause mortality. Conclusions Muscle metrics derived from CT scans at T12 level provide valuable prognostic information which could enhance the role of chest CT in muscle assessment among HD patients.