Early diagnosis of dengue: Diagnostic utility of the SD BIOLINE Dengue Duo rapid test in Reunion Island

BackgroundIn Reunion Island, dengue outbreaks have been occurring since 2018. The healthcare facilities are facing the problem of managing a massive influx of patients and a growing care burden. The aim of this study was to evaluate the performance of the SD Bioline Dengue Duo rapid diagnostic test in adults consulting at an emergency department during the 2019 epidemic. Methodology/Principal findingsThis retrospective study of diagnostic accuracy included patients over 18 years old, suspected of dengue, who were admitted to emergency units of the University Hospital of Reunion between the 1st of January and 30th of June, 2019, and were tested for dengue fever with the SD Bioline Dengue Duo rapid diagnostic test and reverse transcriptase polymerase chain reaction. Over the study period, 2099 patients were screened retrospectively. Of them, 671 patients matched the inclusion criteria. The overall rapid diagnostic test performance was 42% for sensitivity and 15% for specificity. The non-structural 1 antigen component had a good specificity of 82% but a low sensitivity of 12%. The immunoglobulin M component had a sensitivity of 28% and a specificity of 33%. Sensitivities were slightly improved beyond the 5th day of illness compared to the early stage for all components, but only the non-structural 1 antigen component had a better specificity of 91%. Furthermore, predictive values were low and post-test probabilities never improved pre-test probabilities in our setting. Conclusions/SignificanceThese results suggest that the SD Bioline Dengue Duo RDT did not achieve sufficient performance levels to rule in, or discard, an early point of care dengue diagnosis in the emergency department during the 2019 epidemic in Reunion. Author summaryDengue fever is the most common mosquito-borne viral disease. Most often mild, it can progress to a severe form that can lead to death. Since 2018, dengue outbreaks have occurred in Reunion Island, a French overseas territory, with an increasing number of confirmed cases and related deaths reported over these years. The care burden of dengue during epidemics often exceeds the capacity of health care facilities. To optimize the management of cases, it is necessary to diagnose infected patients early. However, clinical diagnosis is difficult as dengue occurs as an influenza-like illness with broad spectrum and non-specific symptoms, and laboratory confirmation is expensive, not immediate and not always available. Therefore, rapid diagnostic tests (RDT) have been developed and could serve as a sensitive, specific, robust point of care diagnostic tool. Although promising, RDT performance is variable depending on the setting. In this study, we evaluated the performance of the SD Bioline Dengue Duo RDT in emergency departments of Reunion during the 2019 epidemic. Results suggest that the SD Bioline Dengue Duo RDT did not achieve sufficient performance levels to rule in or discard an early point of care dengue diagnosis in our setting.