The association between the Acute Physiology Score and sepsis in ICU non-surviving patients with inflammatory bowel disease: a retrospective cohort study from the eICU-CRD

Background Sepsis significantly contributes to ICU mortality in inflammatory bowel disease (IBD) patients. Early risk stratification remains challenging. Methods This retrospective cohort study utilized the eICU-CRD database, analyzing 190 adult IBD patients who died during ICU admission. We employed weighted logistic regression, restricted cubic splines, and XGBoost to evaluate the association between Acute Physiology Score (APS) and sepsis. Results Among 190 non-survivors (55 with sepsis), the sepsis group demonstrated significantly higher APS scores (49.71 ± 23.25 vs. 40.66 ± 18.78, p = 0.015). After full adjustment, APS remained independently associated with sepsis (OR = 1.027, 95% CI: 1.009–1.045, p = 0.004). Quartile analysis revealed a markedly elevated risk in the highest APS quartile (Q4 vs. Q1: OR = 4.856, 95% CI: 1.675–15.713, p = 0.005). XGBoost with SHAP analysis ranked APS as the second most important predictor. Subgroup analyses showed enhanced predictive performance in elderly (≥60 years) and male patients. APS positively correlated with anion gap ( p = 0.044) and lactate ( p = 0.018), and negatively with bicarbonate ( p < 0.001). Conclusion APS independently associated with sepsis in ICU non-surviving IBD patients. Given the small sample and study design, these findings are hypothesis-generating and restricted to this subgroup.