Baseline characteristics of patients with SFTS
A total of 65 patients were included in the study. Table 2 shows the demographic and baseline clinical characteristics of the patients with SFTS. Of the patients, 37 (56.9%) were male, and the mean age was 63.7 ± 14.0 years. All patients were inhabitants of Jeju Island. The mean CCI was very low at 0.5 ± 0.8. Most patients (85%) were exposed to the virus through occupational and outdoor activities, with agricultural activities being the most common route of exposure. Some patients did not know whether they had been bitten by ticks. Most cases occurred in summer, followed by autumn. The mean time from symptoms to diagnosis of SFTS was 5.8 ± 3.3 days, and most cases were confirmed within two days of admission. The mean initial MODS was 2.7 ± 2.5, and the mean SFTS viral load was 82,115,042 ± 643,558,056. The 30-day mortality rate was 13.4%, and 30 patients (46.2%) were admitted to the intensive care unit. Initial laboratory findings revealed neutropaenia, thrombocytopaenia, increased liver enzymes, increased creatine kinase (CK), lactate dehydrogenase (LDH), and activated partial thromboplastin time (aPTT).
In the comparison of the recovered group and death group with SFTS, male patients and older ages showed a tendency for inclusion in the death group. There were no significant differences in comorbidities, exposure type, tick bite history, or seasonal occurrence in either group. However, the mortality of SFTS showed an increasing trend in the spring season. A higher SFTS viral load and MODS were associated with the death group more than with the recovered group. Vasopressor, mechanical ventilation, and CRRT were applied in the death group. There were no significant differences in the application of therapeutic plasma exchange, immunoglobulin, or anti-IL-6 antagonist between the groups. Most fatal cases were deceased within one week of admission.
The initial levels of neutropaenia and thrombocytopaenia could not distinguish whether SFTS patients would be included in the recovered group or death group. However, liver enzymes, aPTT, CK and LDH were significantly different between the two groups.