# Abdominal computed tomography–assessed muscle quality and its prognostic value in patients with advanced chronic kidney disease initiating hemodialysis

## TL;DR

Low muscle quality in abdominal CT scans predicts higher death risk in patients starting hemodialysis for advanced kidney disease.

## Contribution

Demonstrates that skeletal muscle density (SMD) is a better mortality predictor than skeletal muscle index (SMI) in hemodialysis patients.

## Key findings

- Low SMD is independently linked to higher all-cause mortality in hemodialysis patients.
- SMD negatively correlates with BMI, unlike SMI, suggesting it reflects dysfunctional sarcopenia better.
- Male sex, younger age, lower BMI, and higher albumin are associated with higher SMD.

## Abstract

Skeletal muscle density (SMD), assessed via L3 level computed tomography (CT), is a critical marker of muscle quality with remarkable prognostic value in various clinical settings. This study investigates prognostic values of the SMD of abdominal CT images and to verifies its relationship with other variables indicating sarcopenia in patients with advanced chronic kidney disease (CKD) patients.

All 458 patients initiating hemodialysis for maintenance were enrolled in this retrospective study. The sex-specific cut-off values of the SMD and skeletal muscle index (SMI) of L3 level abdominal CT were obtained by drawing the receiver operating characteristic curve for mortality. Cut-offs for identifying low SMD and SMI groups were applied.

The mean age of all patients was 67 years, and 300 (65.6%) patients were male. A total of 204 (44.5%) patients died. In the fully adjusted Cox regression analysis, patients with low SMD had a higher risk of death than those with SMD above the reference cut-off (adjusted hazard ratio (adjHR): 1.805 95% confidence interval (CI): 1.263–2.579, p-value < 0.001). The continuous variable SMD had a prognostic value in the multivariate Cox proportional analysis (adjHR: 0.961, 95% CI: 0.942–0.980, p-value <0.001), while the continuous variable SMI did not have prognostic value after adjustment (adjHR: 1.002, 95% CI: 0.986–1.019, p-value = 0.778). The multivariate regression analysis for SMD with the clinical variable showed that male sex, younger age, lower body mass index (BMI), and higher albumin remained significantly and independently associated with higher SMD. SMD showed an inverse correlation with BMI in contrast to SMI.

The low SMD assessed by abdominal CT is independently associated with all-cause mortality in patients with advanced CKD initiating hemodialysis. In contrast to SMI, SMD showed a negative correlation with BMI, indicating that SMD might reflect dysfunctional sarcopenia better from perspective of the obesity paradox of CKD in this study population.