Admission D-Dimer-to-Albumin Ratio as a Predictor of Poor Prognosis in Patients with Severe Fever with Thrombocytopenia Syndrome: A Retrospective Cohort Study.

Abstract

Purpose: Severe fever with thrombocytopenia syndrome (SFTS) is a severe viral infection associated with rapid clinical deterioration and high mortality. This study evaluated the prognostic value of the D-dimer-to-albumin ratio (DAR) in hospitalized patients with SFTS.

Patients and methods: A total of 387 patients with SFTS were retrospectively included. Correlations between biomarkers and SFTSV RNA levels were evaluated by Spearman analysis. The prognostic performance of DAR and other candidate biomarkers was assessed using ROC analysis and DeLong's test. Multivariable Cox regression and Kaplan-Meier survival analyses were performed to determine the independent prognostic value of DAR.

Results: Of the 387 included patients, 314 (81.1%) survived and 73 (18.9%) died within 28 days after admission. Among the evaluated biomarkers, DAR showed the strongest correlation with SFTSV RNA level (r = 0.438, P < 0.001). DAR also demonstrated the best discriminative ability for predicting 28-day mortality (AUC=0.810, 95% CI, 0.745-0.874). Its prognostic performance was significantly better than that of PLR, CRP, ALB/PLT, LDH/ALB, FAR, and SII, and was comparable to that of NLR and PCT. The optimal cutoff value for DAR was 0.087, with a sensitivity of 73.8% and a specificity of 79.4%, and the highest Youden index. In univariate Cox regression analysis, patients with DAR >0.087 had a significantly increased risk of 28-day mortality (HR = 7.026, 95% CI: 4.228-11.677; P < 0.001). In multivariable Cox regression analysis adjusted for age, sex, cardiovascular comorbidity, neurologic symptoms, bleeding manifestations, SFTSV RNA viral load, onset-to-admission interval, and year of disease onset, DAR remained independently associated with poor outcome (adjusted HR, 4.475; 95% CI, 2.635-7.600; P < 0.001). This association remained significant when DAR was analyzed as a continuous variable. Kaplan-Meier analysis further showed significantly lower survival probability in patients with DAR >0.087.

Conclusion: DAR was significantly associated with poor prognosis in hospitalized patients with SFTS. As a simple and readily available admission-based biomarker, DAR may be useful for early risk stratification and clinical monitoring.