Accuracy of Rapid Tests for the Diagnosis of Acute Dengue in Southern Nigeria

Dengue is an emerging public health concern in West Africa. Although rapid diagnostic tests (RDTs) have facilitated dengue diagnosis, surveillance, and outbreak detection in other endemic regions, there is a paucity of data on their accuracy in African populations. Our objective was to evaluate the diagnostic accuracy of commercial dengue RDTs in southern Nigeria. A retrospective cross-sectional study was conducted in Benin City, Nigeria, using archived plasma samples previously tested with reverse transcriptase-polymerase chain reaction (RT-PCR) as the reference method. Laboratory personnel blinded to the reference test results evaluated a dengue nonstructural (NS) 1 antigen RDT and a combined IgM/IgG antibody test (assessing the individual antibody components separately). Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were estimated for NS1 antigen, IgM, and IgG and reported with 95% confidence intervals (CIs). Of 145 samples selected for the evaluation, 95 (65.5%) were dengue RT-PCR-positive. The sensitivity, specificity, PPV, and NPV of the NS1 antigen RDT with 95% CI were 94.7% (91.5%-98.5%), 100% (98.7%-100.0%), 100% (97.9%-100.0%), and 90.9% (83.5%-98.5%), respectively; its overall accuracy was 96.6% in comparison with 53.8% for IgG and 31.7% for IgM. The area under the receiver operating characteristic curve was 0.974 for NS1 antigen, 0.5 for IgG, and 0.427 for IgM. Although both IgG and IgM components of the antibody RDT evaluated demonstrated poor diagnostic metrics for acute dengue detection, the NS1 antigen RDT had excellent diagnostic parameters, showing promise as a faster alternative for primary diagnosis and routine surveillance of dengue in Southern Nigeria.