Blood Urea Nitrogen–to–Serum Albumin Ratio Predicts Fatal Outcomes in Severe Fever with Thrombocytopenia Syndrome Patients

Abstract

ABSTRACT. There are no effective therapies for severe fever with thrombocytopenia syndrome (SFTS), and existing predictors of mortality are still controversial. This retrospective study aimed to identify reliable early-stage indicators for predicting fatal outcomes in 217 patients hospitalized with an SFTS diagnosis between March 2021 and November 2023; 157 of the patients survived, and 60 died. Demographics, clinical characteristics, and laboratory parameters were reassessed in both groups. The mean age of participants was 64.0 (interquartile range: 54.5–71.0) years, and 42.4% (92/217) were males. Based on a multivariate Cox regression analysis, the blood urea nitrogen–to–serum albumin ratio (BAR) (hazard ratio [HR]:4.751; 95% CI: 2.208–10.226; P <0.001), procalcitonin level (HR: 1.946; 95% CI: 1.080–3.507; P = 0.027), and central nervous system symptoms (HR: 3.257; 95% CI, 1.628–6.513; P = 0.001) were independent risk factors for mortality in SFTS patients. According to a receiver operating characteristic curve analysis, a BAR with an area under the curve of 0.913 (95% CI: 0.873–0.953; P <0.001), a sensitivity of 76.7%, and a specificity of 90.4% showed better predictive performance for fatal outcomes than other classical indicators reported. The Kaplan-Meier survival curve confirmed that an increased BAR was linked with an unfavorable prognosis in SFTS patients (P <0.001 by log-rank test). In conclusion, the results indicate that high BAR levels are markedly related to substandard outcomes and are a reliable and readily accessible predictor of fatal outcomes in SFTS patients.