Association between hemoglobin-to-red blood cell distribution width ratio and 28-day all-cause mortality in patients with acute kidney injury: A cross-sectional study.

BackgroundThe prognostic significance of the hemoglobin-to-red blood cell distribution width ratio (HRR) for 28-day all-cause mortality remains incompletely characterized in patients with acute kidney injury.MethodsThis cross-sectional study included 27,670 patients with acute kidney injury from the Medical Information Mart for Intensive Care-IV database (2008-2022). Multivariable Cox regression, Kaplan-Meier survival analysis, and receiver operating characteristic curve analysis were performed.ResultsPatients were stratified by HRR tertiles: T1 (1.84-6.4), T2 (6.4-8.37), and T3 (8.37-15.5). Mortality rates differed significantly across tertiles (25.2% vs. 14% vs. 8.9%, p < 0.001). Kaplan-Meier analysis showed a significantly higher mortality risk in the lower HRR tertiles (log-rank p < 0.0001). After full adjustment for potential confounders, the hazard ratios were 0.68 (95% confidence interval: 0.63-0.74) for T2 and 0.58 (95% confidence interval: 0.52-0.65) for T3, compared with T1. Receiver operating characteristic curve analysis identified an optimal HRR cutoff value of 6.53 (area under the curve: 0.657, 95% confidence interval: 0.648-0.666) for risk stratification.ConclusionLower HRR values were independently associated with an increased risk of 28-day mortality in critically ill patients, with a practical cutoff of 6.53 for clinical application.