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.Materials and 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.Conclusion: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.

Hospitalisations and outpatient visits for undifferentiated fever attributable to scrub typhus in rural South India: Retrospective cohort and nested case-control study

“…The scope for presumptive treatment of stable fever patients managed as outpatients seems more doubtful, as only a small proportion of these cases may be due to scrub typhus, even in settings where the sero-prevalence exceeds 15%. This confirms the role for rapid diagnostic tests or risk scoring based on clinical findings [21] particularly in outpatients.…”

Acute undifferentiated febrile illness: Protocol in emergency department

“…[ 11 ] Similar results were reported by a study conducted by Mitra et al . [ 13 ] that 78 (98.7%) patients of dengue fever had thrombocytopenia. Previous studies have highlighted the correlation of thrombocytopenia and dengue hemorrhage fever.…”

“…The score should include total leucocyte count, platelet count, ALT, AST, serum bilirubin, SpO 2 levels and altered sensorium. [ 13 ]…”

Scrub typhus infection, not a benign disease: an experience from a tertiary care center in Northern India

“…Various studies have tried to bring forth a clinical score to differentiate scrub typhus and other undifferentiated febrile illnesses like dengue in order to facilitate a prompt diagnosis by primary care physicians who may not have immediate access to confirmatory tests [18,19]. In a study by Varghese et al (n=50), a combination of elevated transaminases, thrombocytopenia and leucocytosis displayed 80% specificity and positive predictive value for diagnosis of scrub typhus [18].…”