# Association between hemoglobin variability and mortality in hemodialysis patients: a retrospective cohort study

## TL;DR

This study finds that hemoglobin variability is linked to higher mortality in hemodialysis patients, with specific measures like Hb coefficient of variation and abnormal ratio being strong predictors.

## Contribution

The study identifies hemoglobin variability measures as independent mortality predictors in hemodialysis patients, offering new clinical insights for risk stratification.

## Key findings

- Hemoglobin coefficient of variation (CV) and residual SD are strongly associated with increased mortality risk in hemodialysis patients.
- Hemoglobin abnormal ratio is an independent predictor of mortality with a hazard ratio of 2.30.
- Results were consistent in a subgroup of patients with at least 10 CBC tests, confirming robustness.

## Abstract

Patients undergoing hemodialysis (HD) face high mortality rates. Monitoring specific laboratory parameters and their derivatives, including hemoglobin (Hb) and its variability, is crucial for improving clinical management and patient outcomes. However, the association between hemoglobin variability and mortality in HD patients remains controversial.

A total of 652 HD patients treated at Wenzhou Traditional Chinese Medicine Hospital of Zhejiang Chinese Medical University were included based on predefined criteria. Patients were divided into survival group and death group based on mortality status during the study period for univariate analysis. Based on univariate results, the following parameters representing Hb variability (Hb-Var) were studied: Hb standard deviation (SD), Hb residual SD, Hb coefficient of variation (CV), and Hb abnormal ratio. Cut-off values for each parameter were determined using ROC curves. Patients were stratified into high-risk group and low-risk group based on these cut-off values. Survival analysis was performed using multivariable Cox regression to obtain hazard ratios (HRs) and p-values for each parameter. To ensure robustness, we repeated the same analyses in the subgroup of patients with at least 10 CBC tests.

The results of univariate analysis showed that there were statistically significant differences in age (p < 0.001), mean Hb (p = 0.002), Hb CV (p = 0.007), Hb residual SD (p < 0.001), and Hb abnormal ratio (p = 0.001). ROC curve analysis yielded the following AUC values: Mean Hb HR = 0.37 (95% CI: 0.23–0.59, p < 0.001), Hb SD HR = 1.72 (95% CI: 1.09–2.72, p = 0.019), Hb residual SD HR = 1.87 (95% CI: 1.20–2.91, p = 0.006), Hb CV HR = 2.12 (95% CI: 1.34–3.35, p = 0.001), Hb abnormal ratio HR = 2.30 (95% CI:1.43–3.69, p < 0.001). The results of the subgroup were largely similar.

Hb-Var included Hb abnormal ratio, Hb residual SD and Hb CV are independent factors associated with mortality in hemodialysis patients.