Comparing the Diagnostic Accuracy of Point-of-Care Lateral Flow Antigen Testing for SARS-CoV-2 with RT-PCR in Primary Care (REAP-2)

Abstract

Background: Testing for COVID-19 with quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) may result in delayed detection of disease. Antigen detection via lateral flow testing (LFT) is faster and amenable to population-wide testing strategies. Our study assesses the diagnostic accuracy of LFT compared to RT-PCR on the same primarycare patients in Austria. Methods: Patients with mild to moderate flu-like symptoms attending a general practice network in an Austrian district (October 22 to November 30, 2020) received clinical assessment including LFT. All suspected COVID-19 cases obtained additional RT-PCR and were divided into two groups: Group 1 (true reactive): suspected cases with reactive LFT and positive RT-PCR; and Group 2 (false non-reactive): suspected cases with a non-reactive LFT but positive RT-PCR. Findings: Of the 2,562 symptomatic patients, 1,037 were suspected of COVID-19 and 826 (79.7%) patients tested RT-PCR positive. Among patients with positive RT-PCR, 788/826 tested LFT reactive (Group 1) and 38 (4.6%) non-reactive (Group 2).

Daily testing for contacts of individuals with SARS-CoV-2 infection and attendance and SARS-CoV-2 transmission in English secondary schools and colleges: an open-label, cluster-randomised trial

“…Previous estimates for the performance of antigen LFDs compared with PCR testing have varied markedly. 7,9,26 We estimated the overall sensitivity of school-based LFD testing in largely asymptomatic individuals as 53%ie, within the range of previously reported rates. It is worth noting that our findings on transmission in this study are in the context of this level of performance.…”

“…Daily testing with antigen lateral flow devices (LFDs) is feasible, 6 with rapid turnaround times, relatively low cost, and good detection of the virus. 7 , 8 , 9 In addition to allowing students and staff to remain at school, daily contact testing might make regular asymptomatic testing more popular and improve contact reporting by removing the social penalty of positive cases triggering isolation in contacts. 10 This in turn might improve case detection and therefore might even reduce transmission.…”

Letter to the Editor regarding Leber W, Lammel O, Siebenhofer A, Redlberger-Fritz M, Panovska-Griffiths J, Czypionka T. Comparing the diagnostic accuracy of point-of-care lateral flow antigen testing for SARS-CoV-2 with RT-PCR in primary care (REAP-2)

“…Reporting on the accuracy of lateral flow antigen tests (LFT) for SARS-CoV-2 in primary care, Leber and colleagues stated the tests to have a sensitivity of 95.4% (judged comparable to RT-PCR) and specificity of 89.1% (lower than clinically validated tests reported to the European Centre for Disease Prevention and Control) [1] .…”

Response to the letter by Prof Jonathan Deeks to the Lancet EClinicalMedicine editor

“…We thank Prof Deeks for taking the time to read our study and respond to our published manuscript [1]. He argues that "The high sensitivity [of the study] is created by a flaw in the study design, as has the low specificity"; that "Incomplete verification linked to the result of the LFT" has led to the sensitivity being overestimated and the specificity being underestimated; and that the 1525 patients with "negative" LFT were "intentionally excluded from verification".…”

“…Specifically, on 22nd October 2021, Austria published guidelines recommending offer of LFT to symptomatic patients attending healthcare settings, including primary care. Our paper (REAP2) evaluates the pragmatic implementation of these guidelines across a large primary care network of 20 general practices in the district of Liezen [1]. The network was set up on recommendation of the initial study (REAP1) evaluating RT-PCR testing in a single general practice [2] and in preparation for a looming second COVID-19 wave in the autumn 2020.…”