Objective:To explore forecast indicators for the prognosis of sepsis in adult extremely severe burn patients.Methods:Case data of adults with extremely severe burns combined with sepsis admitted to the Second Affiliated Hospital of Zhejiang University School of Medicine from January 2017 to December 2021 were retrospectively collected. According to the prognosis, all patients were divided into a death group and a survival group. The general conditions of the two groups were compared. The clinical symptoms, vital signs, platelet count (PLT), white blood cell count (WBC), neutrophil ratio, procalcitonin (PCT), blood sodium, blood glucose, hemoglobin and albumin levels at diagnosis of sepsis were also compared between the two groups. The independent sample t test, Mann?Whitney U test, or Fisher's exact probability test was used for group comparison. Variables with statistical significance in univariate analysis were included in the Cox regression model for multivariate analysis to assess the effect of each index on the outcome of extremely severe burn patients with sepsis. The predictive value of each index for sepsis outcome was analyzed by the receiver operating characteristic curve (ROC). Results:A total of 60 patients with particularly severe burn sepsis were selected, including 41 males and 19 females aged 18 to 84 years. The diagnosis time of sepsis was 14 (7, 24) days after injury. There were 29 patients in the death group and 31 patients in the survival group, and the mortality rate was 48.3%. Compared with the survival group, PLT and hemoglobin levels in the death group decreased significantly (both P<0.05), and PCT and blood sodium levels increased significantly (both P<0.05), while the other indicators did not change significantly (all P>0.05). The results of multivariate Cox regression analysis showed that hemoglobin ( HR=0.936, 95% CI: 0.935-0.991) and serum sodium levels ( HR=1.031, 95% CI: 1.010-1.052) at the time of sepsis diagnosis were independent risk factors affecting the prognosis of sepsis in extra-severe burn patients (both P<0.05). ROC curve analysis showed that the AUCs of hemoglobin, blood sodium and PCT for predicting the prognosis of extremely severe burn patients with sepsis were 0.747, 0.811 and 0.690, respectively (all P<0.05). The cut-off value of hemoglobin for predicting prognosis was 77 g/L, with a sensitivity of 69.0% and specificity of 74.2%. The cut-off value of blood sodium for predicting prognosis was 138 mmol/L, with a sensitivity of 89.7% and specificity of 61.3%. The cut-off value of PCT was 3.51 μg/L, with a sensitivity of 65.5% and specificity of 74.2%. Conclusions:Hemoglobin, blood sodium and PCT may be predictors of outcome in extremely severe burn patients with sepsis.