Hematologic and metabolic indices for predicting 28-day mortality in sepsis patients: a retrospective intensive care cohort study

Background Sepsis remains a leading cause of mortality in critically ill patients, and early risk stratification is essential for improving clinical outcomes. Recently, hematological and metabolic indices derived from routine laboratory parameters have emerged as potential prognostic biomarkers. This study aimed to evaluate the predictive value of the hemoglobin-to-red cell distribution width ratio (HRR), red cell distribution width-to-albumin ratio (RAR), triglyceride–glucose (TyG) index, and uric acid-to-albumin ratio (UA/Alb) for 28-day mortality in patients with sepsis. Methods This retrospective cohort study included 805 adult patients with sepsis admitted to the intensive care units of two tertiary centers between January 2020 and September 2025. Demographic data, clinical severity scores (qSOFA, SOFA, APACHE II, SAPS II), and laboratory parameters obtained within the first 24 h of ICU admission were analyzed. The primary outcome was 28-day all-cause mortality. Receiver operating characteristic (ROC) curve analysis was performed to assess discriminative performance, and logistic regression analyses were conducted to identify independent predictors of mortality. Results Non-survivors had significantly higher disease severity scores and exhibited a distinct biochemical profile characterized by lower hemoglobin and albumin levels and higher RDW, uric acid, triglyceride, and glucose levels (all p < 0.001). All evaluated indices were significantly associated with mortality. The UA/Alb ratio showed the highest predictive performance (AUC: 0.968), followed by the TyG index (AUC: 0.916) and RAR (AUC: 0.900), while HRR demonstrated moderate discrimination (AUC: 0.771). In multivariable analysis, the UA/Alb ratio (OR: 28.47, 95% CI: 12.96–62.51; p < 0.001) and SAPS II score remained independent predictors of 28-day mortality. Conclusion Hematological and metabolic indices are strongly associated with and may improve early prediction of mortality in septic patients. Among these, the UA/Alb demonstrated the highest discriminative performance in this cohort and remained associated with mortality after adjustment; however, its independence from established severity scores should be interpreted with caution.