Reduced skeletal muscle index during follow-up as a mortality risk factor in maintenance hemodialysis patients with end-stage renal disease.

BACKGROUND AND

OBJECTIVE

The obesity paradox is recognized in End-Stage Renal Disease (ESRD) patients on hemodialysis, but the specific impact of body composition and its changes on survival remains unclear. This study assesses the prognostic value of baseline metrics and pre- to post-dialysis changes.

METHODS

Patients with ESRD undergoing maintenance hemodialysis at institutions A and B were retrospectively enrolled. Abdominal CT was quantitatively analyzed by delineating Regions of Interest (ROI) at baseline and two years after dialysis. Categorical and continuous variables were compared using Chi-square and independent t-tests. Significant variables entered a Cox regression model to estimate Hazard Ratios (HRs) and 95% Confidence Intervals (CIs). Receiver Operating Characteristic (ROC) curves identified optimal cutoff values. Absolute change (Δ) was defined as pre- minus post-dialysis values, and relative change (δ) as Δ divided by the pre-dialysis value.

RESULTS

The internal and external validation cohorts were from Institutions A and B. The internal cohort included 187 ESRD patients on maintenance hemodialysis (113 males, 74 females; mean age, 52.43 ± 19.01 years). Pre-dialysis Visceral Fat Area (VFA) (HR = 1.01, P = 0.036) and Skeletal Muscle Index (SMI) (HR = 0.95, P = 0.042) were independent mortality predictors. Greater ΔSMI during dialysis significantly increased mortality risk (HR = 1.09, P = 0.024), and δSMI similarly indicated elevated risk (HR = 1.03, P = 0.026).

CONCLUSION

Low pre-dialysis SMI is a key predictor of mortality. Larger decreases in SMI (ΔSMI or δSMI) during dialysis increase risk, emphasizing the importance of nutritional support and muscle preservation.