Serum creatinine-to-albumin ratio predicts mortality in hemorrhagic stroke: a novel threshold for risk stratification

Hemorrhagic stroke (HS) is a life-threatening condition with high mortality, particularly in intensive care unit (ICU) settings. The serum creatinine-to-albumin ratio (CAR) has emerged as a novel biomarker integrating renal dysfunction and systemic inflammation, but its prognostic value in HS remains underexplored. This retrospective cohort study analyzed data from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. We included 1,046 adult ICU patients with HS (intracerebral or subarachnoid hemorrhage) and stratified them by CAR quartiles. The primary outcome was 28-day all-cause mortality (ACM). Multivariable Cox regression models adjusted for age, Glasgow Coma Scale (GCS) score, and comorbidities were used to assess associations. Predictive performance was evaluated using receiver operating characteristic (ROC) curves and restricted cubic spline (RCS) analysis. The 28-day mortality increased significantly across CAR quartiles (Q1-Q4: 21.8%, 19.1%, 36.0%, and 40.8%, respectively; P for trend < 0.001). In the fully adjusted model (Model 3), patients in the highest CAR quartile (Q4) had a 2.30-fold higher mortality risk (95% CI: 1.58-3.35; P < 0.001) compared to Q1. CAR demonstrated significantly higher discriminative ability (AUC = 0.612, 95% CI: 0.574-0.650) compared to isolated creatinine (AUC = 0.568) or albumin (AUC = 0.371) measurements (P < 0.01). RCS analysis revealed a nonlinear relationship, with CAR > 0.25 marking a critical threshold for increased mortality risk. CAR is an independent predictor of 28-day mortality in critically ill patients with HS, outperforming traditional single biomarkers. Its clinical accessibility and robust prognostic performance suggest potential utility for early risk stratification and personalized treatment strategies in HS management.