title: Clinical risk-scoring algorithm to forecast scrub typhus severity.
abstract: OBJECTIVE
  To develop a simple risk-scoring system to forecast scrub typhus severity.
  
  
  METHODS
  Seven years' retrospective data of patients diagnosed with scrub typhus from two university-affiliated hospitals in the north of Thailand were analyzed. Patients were categorized into three severity groups: nonsevere, severe, and dead. Predictors for severity were analyzed under multivariable ordinal continuation ratio logistic regression. Significant coefficients were transformed into item score and summed to total scores.
  
  
  RESULTS
  Predictors of scrub typhus severity were age >15 years, (odds ratio [OR] =4.09), pulse rate >100/minute (OR 3.19), crepitation (OR 2.97), serum aspartate aminotransferase >160 IU/L (OR 2.89), serum albumin ≤3.0 g/dL (OR 4.69), and serum creatinine >1.4 mg/dL (OR 8.19). The scores which ranged from 0 to 16, classified patients into three risk levels: non-severe (score ≤5, n=278, 52.8%), severe (score 6-9, n=143, 27.2%), and fatal (score ≥10, n=105, 20.0%). Exact severity classification was obtained in 68.3% of cases. Underestimations of 5.9% and overestimations of 25.8% were clinically acceptable.
  
  
  CONCLUSIONS
  The derived scrub typhus severity score classified patients into their severity levels with high levels of prediction, with clinically acceptable under- and overestimations. This classification may assist clinicians in patient prognostication, investigation, and management. The scoring algorithm should be validated by independent data before adoption into routine clinical practice.
authors.affiliation: Clinical Epidemiology Program, Chiang Mai University, Chiang Mai, Thailand ; Department of Social Medicine, Chiangrai Prachanukroh Hospital, Chiang Rai, Thailand.
authors.forename: Pamornsri
authors.initials: P
authors.lastname: Sriwongpan
authors.affiliation: Department of General Pediatrics, Nakornping Hospital, Chiang Mai, Thailand.
authors.forename: Pornsuda
authors.initials: P
authors.lastname: Krittigamas
authors.affiliation: Department of Medicine, Chonburi Hospital, Chonburi, Thailand.
authors.forename: Hutsaya
authors.initials: H
authors.lastname: Tantipong
authors.affiliation: Clinical Epidemiology Program, Thammasat University, Bangkok, Thailand.
authors.forename: Jayanton
authors.initials: J
authors.lastname: Patumanond
authors.affiliation: Clinical Epidemiology Society at Chiang Mai, Chiang Mai, Thailand.
authors.forename: Chamaiporn
authors.initials: C
authors.lastname: Tawichasri
authors.affiliation: Clinical Epidemiology Program, Chiang Mai University, Chiang Mai, Thailand ; Department of Radiology, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Sirianong
authors.initials: S
authors.lastname: Namwongprom
keywords: clinical prediction rule; prognostic predictors; risk-scoring system; severe scrub typhus