Head-to-head comparison of the accuracy of saliva and nasal rapid antigen SARS-CoV-2 self-testing: cross-sectional study

Ewoud Schuit; Roderick P Venekamp; Irene K Veldhuijzen; Wouter van den Bijllaardt; Suzan D Pas; Joep J J M Stohr; Esther B Lodder; Marloes Hellwich; Richard Molenkamp; Zsofia Igloi; Constantijn Wijers; Irene H Vroom; Carla R S Nagel-Imming; Wanda G H Han; Jan A J W Kluytmans; Susan van den Hof; Janneke H H M van de Wijgert; Karel G M Moons

doi:10.1186/s12916-022-02603-x

Head-to-head comparison of the accuracy of saliva and nasal rapid antigen SARS-CoV-2 self-testing: cross-sectional study

BMC Med. 2022 Oct 24;20(1):406. doi: 10.1186/s12916-022-02603-x.

Authors

Ewoud Schuit^#^{1

2}, Roderick P Venekamp^#¹, Irene K Veldhuijzen³, Wouter van den Bijllaardt^{4

5}, Suzan D Pas^{4

6}, Joep J J M Stohr^{5

7}, Esther B Lodder⁸, Marloes Hellwich⁹, Richard Molenkamp¹⁰, Zsofia Igloi¹⁰, Constantijn Wijers¹¹, Irene H Vroom¹¹, Carla R S Nagel-Imming¹, Wanda G H Han³, Jan A J W Kluytmans¹, Susan van den Hof³, Janneke H H M van de Wijgert^#¹, Karel G M Moons^#^{12

13}

Affiliations

¹ Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
² Cochrane Netherlands, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands.
³ Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Antonie van Leeuwenhoeklaan 9, 3721 MA, Bilthoven, The Netherlands.
⁴ Microvida Laboratory for Medical Microbiology, Amphia Hospital, Molengracht 21, 4818 CK, Breda, The Netherlands.
⁵ Department of Infection Control, Amphia Hospital, Molengracht 21, 4818 CK, Breda, The Netherlands.
⁶ Microvida Laboratory for Medical Microbiology, Bravis Hospital, Boerhaavelaan 25, 4708 AE, Roosendaal, The Netherlands.
⁷ Microvida Laboratory for Medical Microbiology, Elisabeth-TweeSteden Hospital, Hilvarenbeekseweg 60, 5022 GC, Tilburg, The Netherlands.
⁸ Public Health Service West-Brabant, Doornboslaan 225-227, 4816 CZ, Breda, The Netherlands.
⁹ Public Health Service Hart Voor Brabant, Reitseplein 3, 5037 AA, Tilburg, The Netherlands.
¹⁰ Department of Viroscience, Erasmus MC, Doctor Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
¹¹ Public Health Service Rotterdam-Rijnmond, Schiedamsedijk 95, 3011 EN, Rotterdam, The Netherlands.
¹² Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands. k.g.m.moons@umcutrecht.nl.
¹³ Cochrane Netherlands, University Medical Center Utrecht, Utrecht University, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands. k.g.m.moons@umcutrecht.nl.

^# Contributed equally.

Abstract

Background: The diagnostic accuracy of unsupervised self-testing with rapid antigen diagnostic tests (Ag-RDTs) is mostly unknown. We studied the diagnostic accuracy of a self-performed SARS-CoV-2 saliva and nasal Ag-RDT in the general population.

Methods: This large cross-sectional study consecutively included unselected individuals aged ≥ 16 years presenting for SARS-CoV-2 testing at three public health service test sites. Participants underwent molecular test sampling and received two self-tests (the Hangzhou AllTest Biotech saliva self-test and the SD Biosensor nasal self-test by Roche Diagnostics) to perform themselves at home. Diagnostic accuracy of both self-tests was assessed with molecular testing as reference.

Results: Out of 2819 participants, 6.5% had a positive molecular test. Overall sensitivities were 46.7% (39.3-54.2%) for the saliva Ag-RDT and 68.9% (61.6-75.6%) for the nasal Ag-RDT. With a viral load cut-off (≥ 5.2 log10 SARS-CoV-2 E-gene copies/mL) as a proxy of infectiousness, these sensitivities increased to 54.9% (46.4-63.3%) and 83.9% (76.9-89.5%), respectively. For the nasal Ag-RDT, sensitivities were 78.5% (71.1-84.8%) and 22.6% (9.6-41.1%) in those symptomatic and asymptomatic at the time of sampling, which increased to 90.4% (83.8-94.9%) and 38.9% (17.3-64.3%) after applying the viral load cut-off. In those with and without prior SARS-CoV-2 infection, sensitivities were 36.8% (16.3-61.6%) and 72.7% (65.1-79.4%). Specificities were > 99% and > 99%, positive predictive values > 70% and > 90%, and negative predictive values > 95% and > 95%, for the saliva and nasal Ag-RDT, respectively, in most analyses. Most participants considered the self-performing and result interpretation (very) easy for both self-tests.

Conclusions: The Hangzhou AllTest Biotech saliva self Ag-RDT is not reliable for SARS-CoV-2 detection, overall, and in all studied subgroups. The SD Biosensor nasal self Ag-RDT had high sensitivity in individuals with symptoms and in those without prior SARS-CoV-2 infection but low sensitivity in asymptomatic individuals and those with a prior SARS-CoV-2 infection which warrants further investigation.

Keywords: Antigen test; COVID-19; Cross-sectional Study; Diagnostic test accuracy; Nasal test; Rapid antigen detection test; SARS-CoV-2; Saliva test.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antigens, Viral
COVID-19 Testing
COVID-19* / diagnosis
Cross-Sectional Studies
Humans
SARS-CoV-2*
Saliva
Sensitivity and Specificity

Substances

Antigens, Viral