The serum anion gap is associated with the prognosis of coronary artery bypass grafting (CABG): analysis based on the MIMIC-IV database.

OBJECTIVE: The serum anion gap (AG) has been reported to be an important prognostic indicator for patients in intensive care units. To explore the potential relationship between the serum AG and 30-day mortality in patients who underwent CABG. PATIENTS AND METHODS: All data were collected from the Medical Information Mart for Intensive Care Ⅳ (MIMIC-Ⅳ) database. We divided patients into 3 groups according to AG tertiles. The primary outcome of our study was the 30-day mortality of patients who underwent CABG. The relationship between the serum AG and mortality in individuals who underwent CABG was estimated using Cox proportional hazard models. Subgroup analysis for effect modification was conducted with a likelihood ratio test. RESULTS: A total of 5,102 eligible subjects were included in our analysis. After adjusting for confounding factors, every unit increase in the AG was associated with a 22% higher odds of 30-day mortality in patients who underwent CABG [hazard ratio (HR), 95% confidence interval (CI): 1.22, 1.13-1.33] When the AG was converted into a categorical variable, the high AG group had a higher risk of 30-day mortality than the low AG group in the fully adjusted model (HR, 95% CI: 3.99, 1.35-11.76). Tests for trends were statistically significant (p-value < 0.05). Subgroup analysis demonstrated that higher mortality was related to the subgroups of people ≥ 70 years and females. CONCLUSIONS: The serum AG was an independent predictor of short-term prognosis in patients who underwent CABG. A high AG was associated with an increased risk of 30-day mortality after CABG.