Baseline characteristics of SFTS patients.

The role of serum ferritin, an acute-phase inflammatory marker, in predicting mortality in patients with severe fever with thrombocytopenia syndrome (SFTS) is not fully understood. This study aimed to investigate the association between serum ferritin levels and inpatient mortality in patients with SFTS. We conducted a retrospective analysis using data from patients diagnosed with SFTS at the Second Affiliated Hospital of Anhui Medical University between May 2017 and September 2024. The association between serum ferritin levels and in-hospital mortality in patients with SFTS was assessed using Cox regression models and restricted cubic spline (RCS) analysis. The receiver operating characteristic (ROC) curve was used to determine the optimal serum ferritin cut-off value for predicting mortality risk. Kaplan–Meier survival curves were compared for survival rates, and propensity score matching with linear trend testing was applied to ensure robustness. This study included 390 patients with SFTS, of whom 312 survived and 78 did not, yielding an in-hospital mortality rate of 20.0%. Cox regression and RCS analyses demonstrated a significant linear association between higher serum ferritin levels and increased in-hospital mortality in patients with SFTS, indicating that the predicted mortality of patients with SFTS increased with elevated serum ferritin levels beyond a certain threshold. ROC analysis revealed an area under the curve of 0.830, with an optimal serum ferritin cut-off of 3.975 (lg, ng/ml), sensitivity of 0.731, and specificity of 0.830. Clinically, serum ferritin levels above 4 (lg ng/ml), were associated with a substantial increase in mortality risk. Sensitivity analysis supported the robustness of these results. Serum ferritin levels are linearly associated with mortality risk in patients with SFTS, with mortality significantly increasing when serum ferritin levels exceed 10,000 ng/ml. Serum ferritin level may serve as a valuable prognostic biomarker for mortality risk in patients with SFTS.急性期炎症标志物血清铁蛋白（serum ferritin）在重症发热伴血小板减少综合征（severe fever with thrombocytopenia syndrome, SFTS）患者死亡预测中的作用尚未完全阐明。本研究旨在探讨SFTS患者血清铁蛋白水平与住院死亡率之间的关联。本研究回顾性分析了2017年5月至2024年9月期间安徽医科大学第二附属医院收治的确诊SFTS患者的临床数据。采用Cox回归模型与限制性立方样条（restricted cubic spline, RCS）分析，评估SFTS患者血清铁蛋白水平与住院死亡率的关联；通过受试者工作特征（receiver operating characteristic, ROC）曲线确定预测死亡风险的最佳血清铁蛋白截断值；采用Kaplan-Meier生存曲线比较患者生存率，并通过倾向得分匹配结合线性趋势检验以验证结果的稳健性。本研究共纳入390例SFTS患者，其中312例存活，78例死亡，住院死亡率为20.0%。Cox回归与RCS分析结果显示，SFTS患者血清铁蛋白水平升高与住院死亡率增加呈显著线性相关，表明当血清铁蛋白水平超过某一阈值后，SFTS患者的预测死亡风险随铁蛋白水平升高而上升。ROC曲线分析显示，曲线下面积为0.830，最佳血清铁蛋白截断值为3.975（以10为底的对数转换值，单位：ng/ml），灵敏度为0.731，特异度为0.830。临床层面来看，血清铁蛋白水平超过4（对数转换值，ng/ml）时，患者死亡风险显著升高。敏感性分析证实了上述结果的稳健性。SFTS患者血清铁蛋白水平与死亡风险呈线性相关，当血清铁蛋白水平超过10000 ng/ml时，患者死亡风险显著升高。血清铁蛋白水平可作为SFTS患者死亡风险预测的潜在有价值的预后生物标志物。