Performance characteristics of five antigen-detecting rapid diagnostic test (Ag-RDT) for SARS-CoV-2 asymptomatic infection: a head-to-head benchmark comparison

Abstract

Background: Mass testing for early identification and isolation of infectious COVID-19 individuals is efficacious for reducing disease spread. Antigen-detecting rapid diagnostic tests (Ag-RDT) may be suitable for testing strategies; however, benchmark comparisons are scarce.

Methods: We used 286 nasopharyngeal specimens from unexposed asymptomatic individuals collected between December 2020 and January 2021 to assess five Ag-RDTs marketed by Abbott, Siemens, Roche Diagnostics, Lepu Medical, and Surescreen.

Results: For the overall sample, the performance parameters of Ag-RDTs were as follows: Abbott assay, sensitivity 38.6% (95%CI 29.1-48.8) and specificity 99.5% (97-100%); Siemens, sensitivity 51.5% (41.3-61.6) and specificity 98.4% (95.3-99.6); Roche, sensitivity 43.6% (33.7-53.8) and specificity 96.2% (92.4-98.5); Lepu, sensitivity 45.5% (35.6-55.8) and specificity 89.2% (83.8-93.3%); Surescreen, sensitivity 28.8% (20.2-38.6) and specificity 97.8% (94.5-99.4%). For specimens with cycle threshold (Ct) <30 in RT-qPCR, all Ag-RDT achieved a sensitivity ≥70%. The modelled negative- and positive-predictive value for 1% prevalence were >99% and <50%, respectively.

Conclusions: When screening unexposed asymptomatic individuals, two Ag-RDTs achieved sensitivity ≥80% for specimens with Ct<30 and specificity ≥96%. The estimated negative predictive value suggests the suitability of Ag-RDTs for mass screenings of SARS-CoV-2 infection in the general population.

Keywords: Antigen-detecting rapid diagnostic test; Head-to-head comparison; Mass screening; SARS-CoV-2.

Fig. 1

Flow-chart of sample inclusion. All samples were nasopharyngeal swabs collected from unexposed asymptomatic individuals during screening campaigns.

Fig. 2

Sensitivity of the antigen-detecting rapid diagnostic tests according to the cycle threshold value of the RT-qPCR analysis. Bars show the 95% confidence interval of the estimated sensitivity.

Fig. 3

Discordance analysis between Ag-RDTs. Bars show the number of samples for each discordance pattern. Black dots and grey dots indicate the assays showing positive and negative results in each discordance pattern. Table S2 summarizes the cycle threshold distribution across discordances.

Fig. 4

Positive predictive value and negative predictive value according to pre-test probabilities. A: overall sample (n= 286). B: samples with cycle threshold <30 in the RT-qPCR assay. Table S3 provides detailed values and confidence intervals for predicted false negative and false positives in the investigated prevalence.