Title : Illness severity in patients with Severe Fever with Thrombocytopenia Syndrome (SFTS) assessed by Multiple Organ Dysfunction Score (MODS): A guide for physicians in monitoring and treatment decisions
Abstract:
Background: Severe Fever with Thrombocytopenia Syndrome (SFTS) is a viral tick-borne disease with high mortality rates, particularly in East Asia. Despite advances in understanding its pathophysiology, effective treatment strategies remain limited. The Multiple Organ Dysfunction Score (MODS) is a widely recognized tool for assessing organ dysfunction and predicting outcomes. This study aims to evaluate the relationship between MODS and clinical outcomes in SFTS patients, providing guidance for monitoring and treatment decisions.
Methods: We conducted an observational cohort study involving 97 SFTS patients admitted to a single teaching hospital between 2013 and 2023. MODS was calculated based on dysfunction in six organ systems (respiratory, cardiovascular, hepatic, renal, coagulation, neurological). Patients were categorized into four groups based on their MODS at admission and on day 7: MODS 0-1, 2-3, 4-5, and ≥6. Viral load, Interleukin (IL)-6 levels, and other clinical variables were analyzed, and outcomes were assessed through logistic regression, Kaplan-Meier survival curves, and Receiver Operating Characteristic (ROC) curve analyses.
Results: Among total of 97 patients with SFTS, the mean age of the patients was 62.4 years, with a nearly equal distribution of males (53.6%). The changes in MODS values and distributions of SFTS patients from the beginning to one week are as follows: 100% of patients in the initial MODS 0-1 category remained in the 0-1 category after one week, indicating no significant progression of organ dysfunction within this group. A 73.8% of patients initially classified with MODS 2-3 remained in the same category after one week, while 26.2% improved, moving down to the 0-1 category. In the initial MODS 4-5 category, 50% of patients remained staying within the 4-5 range, 42.9% of patients showed improvement, moving down to the 2-3 category, while a small proportion (7.1%) significantly improved, dropping to the 0-1 category. Patients in the highest severity category (MODS ≥6) exhibited varying outcomes. 33.3% remained in the ≥6 category, 37.5% improved to the 4-5 category, and 25% moved to the 2-3 range. A small percentage (4.2%) showed significant recovery, moving down to the 0-1 category. In the ROC curve analysis, the optimal MODS cut-off value for predicting fatality was ≥3.5 (AUC=0.836; sensitivity, 75.0%; specificity of 83.1%). The 7-day mortality rate for patients with MODS ≥6 was 37.5%, compared to 0% for those with MODS 0-1 (p < 0.001). Patients with MODS scores of 4-5 also showed a high 7-day mortality (25.0%, p = 0.006). Higher MODS scores were significantly associated with elevated mortality rates. Viral loads and IL-6 levels were significantly higher in patients with MODS ≥6 compared to those with lower scores (p < 0.001).
Conclusion: MODS is a valuable prognostic tool for assessing disease severity in SFTS patients. Patients with higher MODS scores exhibit increased viral load, elevated IL-6 levels, and greater risk of mortality. The findings support the use of MODS for stratifying patients by severity, guiding clinical decisions regarding intensive care and therapeutic interventions. Monitoring changes in MODS could improve outcomes by identifying patients requiring aggressive treatment early in the course of the disease.
