Abstract: Objective By analyzing the clinical characteristics and mortality factors of severe fever with thrombocytopenia syndrome（STFS） patients, we aim to strengthen the early identification of high-risk mortality cases and provide theoretical basis for clinical prognosis. Method This was retrospective study.A total of 51 patients clinically diagnosed with STFS were enrolled between May 2024 and July 2024 at the Sixth People's Hospital of Shenyang. Epidemiological data were collected. All the patients were divided into two groups as follows based on their outcomes: the survival group and the death group. The clinical characteristics, laboratory tests, complications, and mortality factors of the two groups were compared and analyzed. Result 51 patients enrolled in the present study, with 30 subjects were male and 21 subjects were female, average age 64.82±10.36 years. Among all patients, 33 patients showed regional clustering characteristics. Among all patients, fever is the most common clinical manifestation, followed by anorexia, fatigue, disturbance of consciousness, muscle tremors, nausea and vomiting, and dizziness. Oliguria and cutaneous ecchymosis have a relatively low incidence rate. Compared with the survival group (n=32), the death group (n=19) had a higher incidence of consciousness disorders, muscle tremors, and oliguria. Laboratory tests showed that the expression level of platelet count was decreased, while the expression levels of aspartate aminotransferase, lactate dehydrogenase, urea, creatinine, N-terminal pro-brain natriuretic peptide, cardiac troponin, procalcitonin, ferritin, interleukin-10 (IL-10), Tumor Necrosis Factor-alpha, thrombin time and activated partial thromboplastin time were increased significantly in the death group (P<0.05). Multivariate logistic regression analysis revealed that creatinine, IL-10, muscle tremors, and consciousness disorders were independent risk factors for death in patients with SFTS. ROC curve analysis showed that the areas under the curve for the four prediction models—creatinine alone, IL-10 alone, creatinine combined with IL-10, and the combination of all four factors—were 0.796, 0.799, 0.895, and 0.933, respectively. Conclusion In addition to fever, the most common clinical manifestations in SFTS patients include anorexia, fatigue, disturbance of consciousness, muscle tremor, nausea and vomiting, as well as dizziness. The disease is characterized by rapid progression and high mortality. Elevated levels of creatinine and IL-10, along with muscle tremors and disturbance of consciousness, are potential risk factors for death in SFTS patients. Among prediction models, the four-indicator combined prediction model exhibits the best predictive performance for the mortality risk in SFTS patients.

Key words: Severe fever with thrombocytopenina syndrome, Dabie bandavirus, Clinical characteristics, Mortality factors