Predictive Value of the C-Reactive Protein-to-Albumin Ratio for 28-Day and 90-Day All-Cause Mortality in Critically Ill Patients with Inflammatory Bowel Disease: A Retrospective Cohort Study

Background and Aims: The C-reactive protein-to-albumin ratio (CAR) has emerged as a prognostic biomarker in several critical conditions, such as sepsis and malignancies. However, its predictive value for short-term mortality in critically ill patients with inflammatory bowel disease (IBD) remains undetermined. Methods: A retrospective cohort study was conducted using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV, version 3.1) database. A total of 103 critically ill adult patients with IBD were included. Participants were stratified by survival status based on 28-day and 90-day outcomes. Correlation analyses, receiver operating characteristic (ROC) curves, and Kaplan–Meier survival analyses were employed to assess the prognostic utility of CAR. Results: The 28-day and 90-day mortality rates were 9.7% and 16.5%, respectively. Non-survivors exhibited significantly higher CAR levels at both time points (P < 0.05). CAR demonstrated discriminative ability for predicting 28-day mortality (AUC = 0.72, 95% CI: 0.55–0.88) and 90-day mortality (AUC = 0.74, 95% CI: 0.62–0.86). Its prognostic performance was comparable to that of established severity scores such as SAPS II and SOFA. Kaplan–Meier analysis confirmed that patients with elevated CAR had significantly poorer survival outcomes (log-rank P < 0.05). Conclusions: CAR is a strong and independent predictor of short-term mortality in critically ill IBD patients. It offers an accessible and cost-effective tool for early risk stratification in the intensive care setting, potentially complementing or supplementing conventional prognostic models.