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Diagnostic accuracy of a SARS-CoV-2 rapid test and optimal time for seropositivity according to the onset of symptoms

Authors :
Caroline Nespolo de David
Fernanda Hammes Varela
Ivaine Tais Sauthier Sartor
Márcia Polese-Bonatto
Ingrid Rodrigues Fernandes
Gabriela Oliveira Zavaglia
Luciane Beatriz Kern
Charles Francisco Ferreira
Gisele Alsina Nader Bastos
Paulo Márcio Pitrez
Walquiria Aparecida Ferreira de Almeida
Victor Bertollo Gomes Porto
Alexandre Prehn Zavascki
Renato Tetelbom Stein
Marcelo Comerlato Scotta
Source :
Cadernos de Saúde Pública, Vol 38, Iss 1 (2022)
Publication Year :
2022
Publisher :
Escola Nacional de Saúde Pública, Fundação Oswaldo Cruz, 2022.

Abstract

Point-of-care serological tests for SARS-CoV-2 have been used for COVID-19 diagnosis. However, their accuracy over time regarding the onset of symptoms is not fully understood. We aimed to assess the accuracy of a point-of-care lateral flow immunoassay (LFI). Subjects, aged over 18 years, presenting clinical symptoms suggestive of acute SARS-CoV-2 infection were tested once by both nasopharyngeal and oropharyngeal RT-PCR and LFI. The accuracy of LFI was assessed in periodic intervals of three days in relation to the onset of symptoms. The optimal cut-off point was defined as the number of days required to achieve the best sensitivity and specificity. This cut-off point was also used to compare LFI accuracy according to participants’ status: outpatient or hospitalized. In total, 959 patients were included, 379 (39.52%) tested positive for SARS-CoV-2 with RT-PCR, and 272 (28.36%) tested positive with LFI. LFI best performance was achieved after 10 days of the onset of symptoms, with sensitivity and specificity of 84.9% (95%CI: 79.8-89.1) and 94.4% (95%CI: 91.0-96.8), respectively. Although the specificity was similar (94.6% vs. 88.9%, p = 0.051), the sensitivity was higher in hospitalized patients than in outpatients (91.7% vs. 82.1%, p = 0.032) after 10 days of the onset of symptoms. Best sensitivity of point-of-care LFI was found 10 days after the onset of symptoms which may limit its use in acute care. Specificity remained high regardless of the number of days since the onset of symptoms.

Details

Language :
English, Spanish; Castilian, Portuguese
ISSN :
16784464 and 0102311x
Volume :
38
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Cadernos de Saúde Pública
Publication Type :
Academic Journal
Accession number :
edsdoj.6984e03a45194cbc8ebcecb79395db5d
Document Type :
article
Full Text :
https://doi.org/10.1590/0102-311x00069921