Association between serum anion gap and 28-day mortality among patients admitted to the hospital with aortic dissection: a retrospective cohort study with the MIMIC-IV database.

Background: The relationship between serum anion gap (AG) and mortality in aortic dissection (AD) patients remains unclear. This study aimed to elucidate the association between AG levels and 28-day mortality in patients with AD. Methods: This cohort study included AD patients from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Kaplan-Meier survival curves, Cox proportional hazards regression, and restricted cubic spline (RCS) were utilized to analyze the association between AG levels and 28-day mortality. Additionally, receiver operating characteristic (ROC) curves were employed to compare the predictive ability of AG and other serum ions for mortality. Results: A total of 386 AD patients were included in the study. Multivariate analysis demonstrated that higher levels of AG were significantly associated with increased 28-day mortality [hazard ratio (HR) =1.43; 95% confidence interval (CI): 1.25-1.62; P<0.001]. Stratified analysis suggested that higher AG levels were associated with worse prognosis in older and female patients. RCS indicated a non-linear relationship between AG levels and 28-day mortality, with a turning point at 16.568 mEq/L. The ROC curves revealed that AG had a superior ability to predict 28-day mortality compared with other serum ions. Conclusions: Higher levels of AG were associated with increased 28-day mortality in AD patients, especially among elderly and female patients. AG demonstrated greater predictive ability for mortality compared with other serum ions.