ObjectiveTo explore the prognostic risk factors for young patients with hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF) and establish a prognostic model.MethodsA total of 113 young patients (15-44 years old) with HBV-ACLF who were admitted to Department of Infectious Diseases of The Second Affiliated Hospital and Dazu Hospital of Chongqing Medical University from Jan. 2019 to Mar. 2021 were enrolled, and were divided into death group (n＝64) and survival group (n＝49) according to the outcomes. The clinical indexes with significant differences between the 2 groups were screened out by univariate analysis, and the independent risk factors of the prognosis of young HBV-ACLF patients were determined by multivariate binary logistic regression analysis. The prognostic model was established based on the risk indexes, and the receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the model.ResultsThe total fatality of 133 patients was 56.64% (64/113). Univariate analysis showed that white blood cell count, percentage of neutrophil, albumin, serum potassium, serum sodium, prothrombin time, international standardized ratio, creatine kinase isoenzyme, procalcitonin, α-fetoprotein, HBV-DNA level and hepatitis B e antigen level might affect the prognosis of young patients with HBV-ACLF (all P < 0.05). Multivariate binary logistic regression analysis showed that HBV-DNA level≥1×10⁶ IU/mL (odds ratio [OR]＝19.85, 95% confidence interval [CI] 1.64-239.84, P < 0.05), low albumin (OR＝0.71, 95% CI 0.53-0.96, P < 0.05) and low α-fetoprotein (OR＝0.58, 95% CI 0.42-0.81, P < 0.05) were independent risk factors of the prognosis of HBV-ACLF in young patients. The prognosis model was P_prognosis＝1/(1+e^－X), where X＝5.82+2.99×HBV-DNA level (≥1×10⁶ IU/mL was 1, < 1×10⁶ IU/mL was 0)－0.35×albumin (g/L)－0.54×α-fetoprotein (ng/mL), and the area under ROC curve of this model for predicting the prognosis of HBV-ACLF in young patients was 0.98 (95% CI 0.97-1.00, P < 0.001).ConclusionSerum albumin, α-fetoprotein and HBV-DNA level are the independent risk factors of the prognosis of HBV-ACLF in young patients, and the established prognostic model has high predictive value and can provide reference for the preparation of liver transplantation in young HBV-ACLF patients.