Association Between Subcutaneous Adipose Tissue Radiodensity and All-Cause Mortality in Patients Undergoing Hemodialysis: A Retrospective Cohort Study.

Abstract

Objective: Malnutrition and altered body composition are major determinants of mortality in patients undergoing maintenance hemodialysis (HD). We aimed to evaluate the association between subcutaneous adipose tissue radiodensity (SAT-HU) measured on noncontrast abdominal computed tomography (CT) and 5-year all-cause mortality.

Methods: We conducted a retrospective cohort study of 444 maintenance HD patients within the Kaikoukai Healthcare Group who underwent noncontrast CT between 2011 and 2021. The primary exposure was mean SAT-HU at the third lumbar vertebra, categorized into sex-specific tertiles; visceral adipose tissue radiodensity was assessed secondarily. The primary end point was 5-year all-cause mortality. Cox proportional hazards models with multiple imputation were used to estimate adjusted hazard ratios, adjusting for nutritional indices (e.g., body mass index and serum albumin) and other covariates.

Results: During a median follow-up of 3.1 years, 87 deaths (19.6%) occurred. Patients in the highest SAT-HU tertile had lower body mass index, serum albumin and triglyceride levels, and subcutaneous fat area than those in the other tertiles (P < .001). Survival was poorest in the highest SAT-HU tertile (log-rank P < .001). In the fully adjusted model, the highest SAT-HU tertile had higher mortality risk than the lowest tertile (hazard ratio 2.44; 95% confidence interval 1.24-4.80), with a stronger association among patients aged ≥ 75 years (P for interaction = .004). Higher visceral adipose tissue radiodensity was not significantly associated with mortality after adjustment.

Conclusions: Higher SAT-HU independently predicts all-cause mortality in HD, particularly in older patients, and may provide a practical CT-based biomarker for risk stratification beyond conventional nutritional indices.