Positive Association Between the Albumin–Bilirubin (ALBI) Score and Septic Shock in Patients with Escherichia coli Bloodstream Infection: A Retrospective Cohort Study

Yinying Wang, Yingxiu Huang, Ming Hu, Peng ZhenDepartment of Infectious Disease, Beijing Luhe Hospital, Capital Medical University, Beijing, People’s Republic of ChinaCorrespondence: Peng Zhen, Department of Infectious Disease, Beijing Luhe Hospital, Capital Medical University, No. 82, Xinhua South Road, Tongzhou District, Beijing, 101100, People’s Republic of China, Email zhenpeng_1130@163.comBackground: Escherichia coli bloodstream infection (E. coli-BSI) is a common cause of sepsis and may progress to septic shock. However, the association between the albumin–bilirubin (ALBI) score and septic shock in patients with E. coli-BSI remains unclear.Methods: This retrospective cohort study included adults with E. coli-BSI admitted to Beijing Luhe Hospital between 2019 and 2024. The ALBI score was calculated from serum albumin (ALB) and total bilirubin measured within 24 hours of the index blood culture. Associations between ALBI and septic shock were assessed using multivariable logistic regression, restricted cubic splines (RCS), subgroup and sensitivity analyses. Receiver operating characteristic (ROC) analysis assessed discrimination. Exploratory LASSO regression and SHAP analyses evaluated variable contributions.Results: Among 334 patients, 97 (29%) developed septic shock, with the proportions increasing across ALBI tertiles (T1: 5.4%; T2: 27%; T3: 54.5%; p < 0.001). Higher ALBI scores were independently associated with septic shock (adjusted OR, 5.12; 95% CI, 2.37– 11.05; p < 0.001), with higher odds in T3 than T1 (adjusted OR, 7.40; 95% CI, 2.63– 20.83; p < 0.001). The association remained consistent across subgroup and sensitivity analyses. ALBI showed moderate discrimination (AUC, 0.796; 95% CI, 0.745– 0.847), which was inferior to SOFA (AUC, 0.909; 95% CI, 0.877– 0.941; p < 0.001), but comparable to ALB alone (AUC, 0.816; 95% CI, 0.766– 0.865; p = 0.22). Exploratory LASSO and SHAP analyses identified ALBI as an important contributor.Conclusion: Higher ALBI scores were independently associated with septic shock in adults with E. coli-BSI. ALBI showed moderate discrimination but was inferior to SOFA and not significantly better than ALB alone. These findings indicate an association between ALBI and septic shock but do not establish its predictive or clinical utility. Prospective multicenter studies are warranted to determine its clinical value for risk assessment.Keywords: albumin–bilirubin score, ALBI, bloodstream infection, Escherichia coli, septic shock