title: Clinical Score to Differentiate Scrub Typhus and Dengue: A Tool to Differentiate Scrub Typhus and Dengue.
abstract: BACKGROUND
  Dengue and scrub typhus share similar clinical and epidemiological features, and are difficult to differentiate at initial presentation. Many places are endemic to both these infections where they comprise the majority of acute undifferentiated febrile illnesses.
  
  
  METHODS
  We aimed to develop a score that can differentiate scrub typhus from dengue. In this cross-sectional study, 188 cases of scrub typhus and 201 cases of dengue infection who presented to the emergency department or medicine outpatient clinic from September 2012 to April 2013 were included. Univariate followed by multivariate logistic regression analysis was performed to identify clinical features and laboratory results that were significantly different between the two groups. Each variable was assigned scores based on the strength of association and receiver operating characteristics area under the curve (ROC-AUC) was generated and compared. Six scoring models were explored to ascertain the model with the best fit.
  
  
  RESULTS
  Model 2 was developed using the following six variables: oxygen saturation (>90%, ≤90%), total white blood cell count (<4000, 4001-7000 and >7000 cells/cumm), hemoglobin (≤14 and >14 g/dL), total bilirubin (<2 and ≥2 mg/dL), serum glutamic oxaloacetic transaminase (>200 and ≥200 IU/dL), and altered sensorium (present or absent). Each variable was assigned scores based on its strength of association. The AUC-ROC curve (95% confidence interval) for model 2 was 0.84 (0.79-0.89). At the cut off score of 13, the sensitivity and specificity were 85% and 77% respectively, with a higher score favoring dengue.
  
  
  CONCLUSIONS
  In areas of high burden of ST and dengue, model 2 (the "clinical score to differentiate scrub typhus and dengue fever") is a simple and rapid clinical scoring system that may be used to differentiate scrub typhus and dengue at initial presentation.
authors.affiliation: Department of Emergency Medicine, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Shubhanker
authors.initials: S
authors.lastname: Mitra
authors.affiliation: Department of General Medicine, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Ira
authors.initials: I
authors.lastname: Gautam
authors.affiliation: Department of General Medicine, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Mohan
authors.initials: M
authors.lastname: Jambugulam
authors.affiliation: Department of Emergency Medicine, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Kundavaram Paul Prabhakar
authors.initials: KP
authors.lastname: Abhilash
authors.affiliation: Department of Biostatistics, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Vishalakshi
authors.initials: V
authors.lastname: Jayaseeelan
keywords: Clinical score to differentiate scrub typhus and dengue score; dengue fever; scoring system; scrub typhus