J Korean Med Sci.  2020 Mar;35(11):e77. 10.3346/jkms.2020.35.e77.

Clinical Score System to Differentiate Severe Fever with Thrombocytopenia Syndrome Patients from Patients with Scrub Typhus or Hemorrhagic Fever with Renal Syndrome in Korea

  • 1Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea. khsongmd@snu.ac.kr
  • 2Department of Internal Medicine, Kangwon National University Hospital, Kangwon National University School of Medicine, Chuncheon, Korea.
  • 3Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
  • 4Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea.
  • 5Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.


Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high mortality in East Asia. This study aimed to develop, for primary care providers, a prediction score using initial symptoms and basic laboratory blood tests to differentiate between SFTS and other endemic zoonoses in Korea.
Patients aged ≥ 18 years diagnosed with endemic zoonoses during a 3-year period (between January 2015 and December 2017) were retrospectively enrolled from 4 tertiary university hospitals. A prediction score was built based on multivariate logistic regression analyses.
Of 84 patients, 35 with SFTS and 49 with other endemic zoonoses were enrolled. In multivariate logistic regression analysis, independent predictors of SFTS included neurologic symptoms (odds ratio [OR], 12.915; 95% confidence interval [CI], 2.173-76.747), diarrhea (OR, 10.306; 95% CI, 1.588-66.895), leukopenia (< 4,000/mm3) (OR, 19.400; 95% CI, 3.290-114.408), and normal C-reactive protein (< 0.5 mg/dL) (OR, 24.739; 95% CI, 1.812-337.742). We set up a prediction score by assigning one point to each of these four predictors. A score of ≥ 2 had 82.9% sensitivity (95% CI, 71.7%-87.5%) and 95.9% specificity (95% CI, 88.0%-99.2%). The area under the curve of the clinical prediction score was 0.950 (95% CI, 0.903-0.997).
This study finding suggests a simple and useful scoring system to predict SFTS in patients with endemic zoonoses. We expect this strategic approach to facilitate early differentiation of SFTS from other endemic zoonoses, especially by primary care providers, and to improve the clinical outcomes.


Severe Fever with Thrombocytopenia Syndrome; Prediction; Differential Diagnosis; Scrub Typhus; Hemorrhagic Fever with Renal Syndrome

MeSH Terms

C-Reactive Protein
Communicable Diseases, Emerging
Diagnosis, Differential
Far East
Hematologic Tests
Hemorrhagic Fever with Renal Syndrome*
Hospitals, University
Logistic Models
Neurologic Manifestations
Primary Health Care
Retrospective Studies
Scrub Typhus*
Sensitivity and Specificity
C-Reactive Protein
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