Authors (including presenting author) :
Lam RPK (1)(2), Leung JCY (1), Lau MCK (1), Rainer TH (1)(2)
Affiliation :
(1)Department of Emergency Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong (2)Accident and Emergency Department, Queen Mary Hospital
Keyword 2: :
Point-of-care test
Keyword 3: :
Emergency department
Keyword 4: :
Polymerase chain reaction
Introduction :
Emerging evidence shows that routine point-of-care (POC) polymerase chain reaction (PCR) testing of patients with acute respiratory infections (ARIs) for respiratory viruses in the emergency department (ED) can increase the appropriate use of antivirals, shorten the time to antivirals, reduce unnecessary antibiotic use, and facilitate decisions on isolation. However, the accuracy of POC PCR testing in the ED remains unclear.
Objectives :
We aimed to evaluate the accuracy of POC PCR testing for SARS-CoV-2 in adult ED patients with ARIs and to identify the reasons for false positive and negative results.
Methodology :
We conducted a prospective cross-sectional study on adult ED patients with ARIs presenting to Queen Mary Hospital during the COVID-19 wave in Hong Kong between 26 May 2025 and 26 June 2025. A nasal swab was collected for POC PCR testing in the ED after verbal consent by trained research staff using the Xpert® Xpress SARS-CoV-2/Flu/RSV test kit and the automated GeneXpert Instrument System. The reference standard was the independent PCR test results performed by the hospital or government virology laboratory. We evaluated the accuracy of the POC test, including sensitivity and specificity, and the reasons for false positive and negative results.
Result & Outcome :
In total, 50 patients were recruited, of whom 49 had both POC and laboratory results for analysis and 14 (28.6%) were subsequently diagnosed with COVID-19 based on laboratory results. The sensitivity and specificity of the POC PCR tests were 92.9% (95% confidence interval [CI] 64.2% to 99.0%) and 97.1% (95% CI 83.4% to 99.9%), respectively. The only false positive case was likely due to sample contamination during processing in the ED. A review of the presenting symptoms of the only false negative case revealed a lack of nasal symptoms, which might reduce the yield of sampling viral particles using nasal swab compared to nasopharyngeal swab subsequently performed on the ward for laboratory testing. Conclusions ED POC PCR testing for SARS-CoV-2 is highly accurate compared to standard laboratory testing. However, the operating procedures should be improved to prevent sample contamination. For patients without nasal symptoms, a nasopharyngeal swab should be performed to increase the yield of viral detection.
