Utility of SARS-CoV-2 Rapid Antigen Testing for Patient Triage in the Emergency Department: A Clinical Implementation Study in Melbourne, Australia

Background: Early, rapid detection of SARS-CoV-2 is essential in healthcare settings in order to implement appropriate infection control precautions and rapidly assign patients to appropriate care pathways. Rapid testing methods, such as SARS-CoV-2 rapid antigen testing (RAT) may improve patient care, despite a lower sensitivity than real-time PCR (RT-PCR) testing. Methods: Symptomatic patients presenting to an Emergency Department (ED) in Melbourne, Australia, were risk stratified for their likelihood of active COVID-19 infection, and tested by both Abbott Panbio™ COVID-12 Ag test and SARS-CoV-2 RT-PCR. Patients with a positive RAT in the ‘At or High Risk’ COVID-19 group were moved immediately to a COVID-19 ward rather than waiting for a RT-PCR result. Clinical and laboratory data were extracted to determine test performance characteristics and length of stay in the ED. Findings: Analysis of 1762 paired RAT/RT-PCR samples demonstrated an overall sensitivity of 75.5% (95% CI: 69·9-80·4) for the Abbott Panbio™ COVID-12 Ag test, with specificity of 100% (95% CI: 99·8-100). Sensitivity improved with increasing risk for COVID-19 infection, from 72·4% (95% CI: 52·8-87·3) in the ‘No Risk’ cohort to 100% (95% CI: 29·2-100) in the ‘High Risk’ group. Time in the ED for the ‘At/High Risk’ group decreased from 421 minutes (IQR: 281, 525) to 274 minutes (140, 425), p = 0.02. Interpretation: The positive predictive value of a positive RAT in this setting was high, allowing more rapid instigation of COVID-19 positive care pathways and an improvement in patient flow within the ED. Funding Information: This work was funded by the Royal Melbourne Hospital, Melbourne, Australia. Declaration of Interests: The authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.Ethics Approval Statement: This study was approved as a quality assurance activity with Human Research Ethic Committee approval from the Royal Melbourne Hospital (QA2020085).