Prognostic value of red cell distribution width-to-albumin ratio in septic patients with malignancies: A retrospective cohort study based on the MIMIC-IV database

Abstract

Objective: To investigate the prognostic value of red cell distribution width-to-albumin ratio (RAR) in sepsis patients with malignancies and evaluate its association with in-hospital mortality. Methods: The retrospective cohort study was conducted using data extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Participants were stratified into quartiles (Q1–Q4) based on RAR levels measured within 24 hours of intensive care unit admission. The primary outcome was 28-day in-hospital all-cause mortality. Associations between RAR and clinical outcomes were assessed using Kaplan–Meier survival analysis, multivariate Cox proportional hazards regression and restricted cubic spline (RCS) modeling. Predictive performance was further evaluated through receiver operating characteristic (ROC) analysis and decision curve analysis (DCA). Results: A total of 1686 eligible patients were included. Multivariate Cox regression revealed a significant positive association between RAR and 28-day in-hospital mortality (adjusted model 3 HR = 1.12, 95% CI: 1.08–1.16, P < 0.001). Kaplan–Meier curves demonstrated a stepwise decline in survival with increasing RAR levels (28-day survival rate of 75.26% in Q1 vs. 49.88% in Q4, P < 0.001). RCS analysis identified a linear relationship between RAR and the hazard ratios for 28-day in-hospital mortality (P for nonlinearity > 0.05). ROC analysis showed that RAR (area under the curve = 0.624) yielded better prognostic utility than red blood cell distribution width and sequential organ failure assessment, with significant differences confirmed by DeLong's test. RAR also exhibited the best calibration (slope = 1.0109; Brier score = 0.2166) and the highest net clinical benefit in DCA (22%–95%; maximum = 0.162). Subgroup analysis showed consistent results across all groups (P for interaction > 0.05). Conclusions: RAR may serve as an independent prognostic indicator in septic patients with malignancies. Its elevation is significantly associated with increased mortality risk and may aid in the early identification of high-risk individuals and the implementation of targeted interventions. Further prospective, multicenter studies are warranted to validate its clinical applicability and dynamic monitoring potential.