Abstract
WHO recommendations for dengue diagnosis require laboratory facilities. Antibody-based rapid diagnostic tests (RDTs) have performed poorly, and clinical diagnosis remains the mainstay in dengue-endemic countries. We evaluated a combination antigen-antibody RDT for point-of-care testing in a high-prevalence setting. In this prospective cohort study, adults were enrolled from a tertiary infectious disease centre for evaluation of undifferentiated febrile illness from October 2011 to May 2012. SD Bioline Dengue Duo was evaluated at point-of-care against a WHO-based reference standard of viral isolation, RT-PCR, NS1-, IgM-, and IgG-ELISA. 246 adults were enrolled (median age 34 years, range 18–69), of which 197 could be confirmed definitively as either dengue or non-dengue. DENV-2 was the predominant serotype (79.5%) and the ratio of primary to secondary cases was 1∶1.1. There were no test failures and minimal interobserver variation with a Fleiss’ kappa of 0.983 (95% CI 0.827–1.00). Overall sensitivity and specificity were 93.9% (95% CI 88.8–96.8%) and 92.0% (95% CI 81.2–96.9%) respectively. Using WHO clinical criteria alone for diagnosis had similar sensitivities (95.9%, 95% CI 91.4–98.1%) and lower specificities (20.0%, 95% CI 11.2–33.0%). No significant difference in performance was found when testing early versus late presenters, primary versus secondary cases, or DENV-1 versus DENV-2 infections. The use of a combination RDT fulfills WHO ASSURED criteria for point-of-care testing and can enhance dengue diagnosis in an endemic setting. This has the potential to markedly improve clinical management of dengue in the field.
Highlights
Dengue is an important vector-borne disease, with over one billion people at risk in the subtropics and tropics [1]
We analysed the use of the point-of-care test (POCT) in combination with WHO clinical criteria by using either WHO 1997 or WHO 2009 probable dengue criteria as the initial screening method followed by Dengue Duo (NS1/IgM/IgG) for those who were positive by the WHO criteria
The current WHO recommendations for laboratory diagnosis are viral isolation, RTPCR, or non-structural protein 1 (NS1) detection in early illness, and a four-fold rise of dengue-specific antibody titres for patients presenting later [19]
Summary
Dengue is an important vector-borne disease, with over one billion people at risk in the subtropics and tropics [1]. SD Dengue Duo (Standard Diagnostics, Inc., Gyeonggi-do, Korea) was chosen, as it has shown good performance in multiple laboratory-based trials with sensitivities and specificities ranging from 75.5–92.9% and 88.8–100% respectively using frozen serum or plasma samples [10,11,12,13,14]. We evaluated this commercially available assay using whole blood to obtain a reading within 30 minutes of patient presentation
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