On-Field Evaluation of Exdia COVID-19 Antigen Point-of-Care Testing in the Emergency Department During the COVID-19 Pandemic

Abstract

Background: We evaluated the diagnostic performance of the Exdia COVID-19 antigen test (Exdia Ag; Precision Biosensor Inc., Korea) as a point-of-care (POC) test performed in the emergency department (ED) for the rapid detection of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in comparison with the performance of the Real-Q 2019-nCoV Detection KIT (Real-Q; BioSewoom, Korea). Methods: Exdia Ag and Real-Q assays were performed simultaneously for all patients who were admitted to the ED with or without COVID-19 symptoms between December 2021 and March 2022. Results: Among the 2,523 samples analyzed by Real-Q assay, 149 samples (5.9%) showed positive results, and 2,374 samples showed negative results. The overall sensitivity and specificity of the Exdia Ag assay were 77.2% (95% confidence interval [CI], 69.6 – 83.7) and 99.8% (95% CI, 99.6 – 99.9), respectively. The positive and negative predictive values were 96.6% (95% CI, 91.5 – 98.7) and 98.6% (95% CI, 98.1 – 98.9), respectively. The cycle threshold value for 115 concordant Exdia Ag-positive/Real-Q-positive samples was significantly lower than that for 34 discordant Exdia Ag-negative/Real-Q-positive samples (P < 0.0001) Conclusion: The Exdia Ag assay showed good diagnostic performance when the disease prevalence was high and may be useful for POC testing when the rapid detection of SARS-CoV-2 is required for the isolation of patients in the ED.

Keywords

• antigens
• emergency department
• point-of-care testing
• sars-cov-2