A-302 Agreement Assessment Between Molecular and Rapid Tests in Respiratory Viruses Detection

Abstract

Abstract Background Diseases caused by respiratory viruses are the most frequent diseases in humans and have a significant impact on morbidity and mortality worldwide. Due to their transmission nature, these viruses are able to widespread dissemination. The pandemic caused by COVID-19 highlights this potential, however, other respiratory viruses also continue to circulate such as Respiratory Syncytial Virus (RSV) and Influenza (FLU). Efficient diagnostic tools are necessary, especially in endemic regions. Although molecular tests are gold standards, rapid tests (RTs) represent a great alternative once they are more accessible, faster, easier to manage, and can be performed at the point of care. Therefore, this work aimed to evaluate the analytical performance of RTs compared to molecular tests in the detection of viral antigens of RSV or FLU in swab samples. Methods Swab samples in saline solution (n = 60) were tested by qPCR molecular assay Multiplex Alinity m Resp-4-Plex Assay (Abbott Molecular) and RTs immunofluorescence-based (ECO-F RSV ag and ECO-F Influenza A/B—ECO Diagnostica). For the molecular assay, samples were prepared according to the manufacturer's instructions. For RTs, samples were submitted to the extraction buffer, incubated for 10 or 15 minutes respectively, and analyzed by ECO Reader F200 equipment, according to the manufacturer's instructions. It uses a cut-off value ≥1.00 for positive samples and <1.00 for negative samples. Results All negative samples (RSV = 20; FLU = 20) in molecular test were concordant with RTs results. The number of positive samples detected by molecular test was 4 and 16 for FLU and RSV respectively, while RTs detected a lower number of positive samples (FLU = 2; RSV = 10). Both RTs achieved a specificity of 100%; sensibility was 62, 50% for RSV and 50% for FLU. Using Cohen's Kappa index to assess the agreement between the compared tests, it was obtained the expected and observed values of 0.83 and 0.53 for RSV and 0.92 and 0.78 for FLU, which represents an index of 0.649 and 0.625 respectively. These results indicate substantial agreement between the tests, although the sensitivity of the molecular assay was superior. Conclusion Molecular tests can be used to confirm the results of RTs, once they are the gold standard for diagnosis. However, they have a high operational cost, which makes RTs a good alternative to help in the screening of these respiratory diseases, especially in resource-limited settings, allowing effective treatment and management for the patient.