Study design and SFTS patients
We performed a retrospective study on patients with severe fever with
thrombocytopaenia syndrome at Jeju National University Hospital in Jeju
Island, South Korea. This region had the highest incidence of SFTS in
South Korea. The study was approved by the Institutional Review Board
(IRB) at the Jeju National University Hospital (IRB file no.
2021-03-012).
Patients were admitted for confirmed SFTS during May 2013-April 2022,
and these patients were eligible to participate in the study. During the
study period, a total of 84 patients were confirmed to be positive for
small (S) and large (L) segments of SFTSV RNA using real-time RT-PCR,
based on the recommended diagnosis method in South Korea. Of these
confirmed patients, 65 were analysed in the present study.
The demographic and clinical characteristics data were obtained from the
electronic medical records and included the patient demographics,
activity at the time of exposure, history of tick bites, presence of
initial symptoms, vital signs, past medical history, CCI, multiple organ
dysfunction score (MODS) during hospitalization and after 72 h of
treatment (inotropes, intubation, renal replacement therapy, and plasma
exchange), disposition after hospital admission, and 30-day mortality.
The patients’ blood samples were collected at the first visit to the
hospital and then at regular intervals (every two days in the acute
phase, twice a week in the recovery phase during hospitalization, and
every 2 to 3 months after discharge).
Patients were divided into the severe group (SG) and nonsevere group
(NSG). The SG comprised patients with three or more organ dysfunctions
as defined by Sequential Organ Failure Assessment (SOFA) score including
the following: for the lung a PaO2/FiO2 <400 or patients
requiring mechanical ventilation; for the liver a serum bilirubin ≥1.2
mg/dL; for the kidney a serum creatinine ≥1.2 mg/dL, urine output
<500 mL/day or patients requiring haemodialysis; for the
cardiovascular system a mean arterial pressure <70 mmHg or
patients requiring vasopressor; and for the central nervous system a
Glasgow Coma Scale <15, or deceased patients (reference
https://doi.org/10.3947/ic.2022.0073.).