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 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 Patients presenting to an Emergency Department (ED) in Melbourne, Australia, were risk-stratified for their likelihood of active COVID-19 infection, and a non-randomised cohort of patients were tested by both Abbott PanbioTM COVID-19 Ag test (RAT) 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 assessed to determine test performance characteristics; and length of stay in the ED was compared for the different patient cohorts. Findings Analysis of 1762 paired RAT/RT-PCR samples demonstrated an overall sensitivity of 75.5% (206/273; 95% CI: 69.9-80.4) for the Abbott Panbio (TM) COVID-12 Ag test, with specificity of 100% (1489/1489; 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) for those with a positive RAT result to 274 minutes (IQR:140, 425) for those with a negative RAT result, p = 0.02. Interpretation The positive predictive value of a positive RAT in this setting was high, allowing more rapid instigation of COVID-19 care pathways and an improvement in patient flow within the ED. Copyright (C) 2022 The Authors. Published by Elsevier Ltd.

Automated summary

This study evaluated the application of SARS-CoV-2 rapid antigen testing in an emergency department. The results showed that despite lower sensitivity, the positive predictive value of positive results was high, enabling faster implementation of COVID-19 care pathways and improvement in patient flow within the emergency department.