Association between anion gap trajectories and mortality in patients with acute cholangitis: a cohort study

Prior studies have suggested that baseline anion gap (AG) is associated with prognosis in acute cholangitis (AC). however, the association between AG trajectories after ICU admission and clinical outcomes remains unclear. Using data from the Medical Information Mart for Intensive Care IV (MIMIC-IV), we included 861 ICU-admitted patients with AC. AG measurements during the first 96 h after ICU admission were extracted. Latent class growth modeling (LCGM) identified four AG trajectory classes: Class 1 (persistently low), Class 2 (persistently moderate), Class 3 (persistently elevated), and Class 4 (persistently elevated despite decline). Kaplan-Meier analysis and multivariable Cox regression after comprehensive adjustment for confounders were used to assess associations with 28-day and 90-day all-cause mortality. Over all 28-day and 90-day mortality were 16.7% and 26.5%, respectively. Compared with Class 1, Class 3 and Class 4 showed higher adjusted mortality risks (28-day: Class 3 h 2.79, 95% CI 1.55-5.00, p = 0.001; Class 4 h 4.76, 95% CI 2.33-9.72, p < 0.001; 90-day: Class 3 h 2.34, 95% CI 1.49-3.68, p < 0.001; Class 4 h 4.12, 95% CI 2.31-7.36, p < 0.001). These findings suggest that dynamic AG monitoring during the early ICU course may help identify high-risk AC patients and inform clinical management.