Diagnostic accuracy of a SARS-CoV-2 rapid antigen test in real-life clinical settings

Abstract

Background Laboratory tests are a mainstay in managing the COVID-19 pandemic, and high hopes are placed on rapid antigen tests. However, the accuracy of rapid antigen tests in real-life clinical settings is unclear because adequately designed diagnostic accuracy studies are essentially lacking. Objectives We aimed to assess the diagnostic accuracy of a rapid antigen test to diagnose SARS-CoV-2 infection in a primary/ secondary care testing facility. Methods Consecutive individuals presented at a COVID-19 testing facility affiliated to a Swiss University Hospital were recruited (n=1’465%). Nasopharyngeal swabs were obtained, and the Roche/ SD Biosensor rapid antigen test was conducted in-parallel with two real-time PCR (reference standard). Results Among 1’465 patients recruited, RT-PCR was positive in 141 individuals, corresponding to a prevalence of prevalence 9.6%. The Roche/ SD Biosensor rapid antigen test was positive in 94 patients (6.4%), and negative in 1’368 individuals (93.4%). The overall sensitivity of the rapid antigen test was 65.3% (95% confidence interval, CI, 56.8, 73.1), the specificity was 99.9% (95%CI 99.5, 100.0). In asymptomatic individuals, the sensitivity was 44.0% (95%CI 24.4, 65.1). Conclusions The diagnostic accuracy of the SARS-CoV-2 Roche/SD Biosensor rapid antigen test to diagnose a SARS-CoV-2 infection in a primary/ secondary care testing facility was considerably lower compared to manufacturers’ data. Widespread application in this setting might lead to a considerable number of individuals falsely classified as SARS-CoV-2 negative.

The Rapid Antigen Detection Test for SARS-CoV-2 Underestimates the Identification of COVID-19 Positive Cases and Compromises the Diagnosis of the SARS-CoV-2 (K417N/T, E484K, and N501Y) Variants

“…For example, Linares et al (13) reported that patients with less than seven days of symptoms showed a high viral load and a sensitivity of 86.5%, while the sensitivity dropped to 53.8% in asymptomatic patients or lower viral loads using the Panbio COVID-19 Ag Rapid Test Device (Abbot). The same effect was observed using the SD Biosensor-STANDARD Q COVID-19 test, where a sensitivity of 65.3% was observed in symptomatic patients and 44% in asymptomatic patients (14). Krüttgen et al ( 6) using the rapid SARS-CoV-2 antigen test from the Roche manufacturer, indicated that the sensitivity of the assay in 75 NPSs is 100% (Cq≤25), 95% (Cq≤30), 44.8% (Cq≤35), and 22.2% (Cq>35) compared to RT-qPCR.…”

Comparison of Rapid and Automated Antigen Detection Tests for the Diagnosis of SARS-CoV-2 Infection

“…Despite limited sensitivity, the easy-to-perform antigen tests are of great interest where NAAT is unavailable, where prolonged turnaround time (TAT) precludes clinical utility or when it offers a cost-effective solution alternative to RT-PCR. Automated antigen assays have another advantage of high throughput screening possibility, however they had relatively long TAT compared to RAT [ 3 , 9 , 13 , 19 ]. Thereby, further strategies should therefore be evaluated to appropriately position these tools in the diagnostic context.…”

In-House Immunofluorescence Assay for Detection of SARS-CoV-2 Antigens in Cells from Nasopharyngeal Swabs as a Diagnostic Method for COVID-19

“…Previous publications have identified the sensitivity and specificity of other antigen-detection methods, including a meta-analysis of 29 studies on rapid antigen tests that indicate overall pooled sensitivity and specificity as 68% and 99% [ 38 ], and a recent large-scale study on a rapid antigen test (Roche/SD Biosensor) has shown similar diagnostic accuracy with 65% sensitivity and 100% specificity [ 39 ]. The immunofluorescence assay yields comparable sensitivity of 59% and specificity of 98%, owing to cross-reactivity with SARS-CoV.…”