Association of red cell distribution width-to-albumin ratio with ICU outcomes in patients with aortic dissection

Objective Critically ill patients with aortic dissection remain at high risk of adverse ICU outcomes, including ICU mortality. The red cell distribution width-to-albumin ratio (RAR) has been investigated as a prognostic marker in various clinical settings. This study aimed to evaluate the association of RAR with ICU outcomes in patients with aortic dissection. Methods Data were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. ICU mortality was defined as the primary outcome. Secondary outcomes included sepsis during hospitalization/ICU stay, acute kidney injury (AKI), and renal replacement therapy (RRT) use. Receiver operating characteristic (ROC) curve analysis was used to assess the discriminative performance of RAR for ICU mortality. The optimal RAR cutoff was determined using Youden's index and was considered exploratory. Calibration plots and decision curve analysis were used to evaluate model performance. Results RAR showed modest discrimination for ICU mortality (AUC: 0.66; 95% CI: 0.552–0.765). The exploratory cutoff value of RAR was 5.182. Compared with the low-RAR group, the high-RAR group had higher ICU mortality (21.8% vs. 6.7%; P < 0.001), a higher prevalence of sepsis during hospitalization/ICU stay (82.8% vs. 61.1%; P < 0.001), and more frequent RRT use (33.3% vs. 9.4%; P < 0.001). The AUC increased from 0.706 for SOFA alone to 0.731 for SOFA plus RAR, indicating only limited incremental discrimination. Conclusion Higher early-ICU RAR was associated with ICU mortality and other adverse ICU outcomes in patients with aortic dissection, but its discrimination was modest, its incremental value beyond SOFA was limited, and external validation is required.