Nasopharyngeal Panbio COVID-19 Antigen Performed at Point-of-Care Has a High Sensitivity in Symptomatic and Asymptomatic Patients With Higher Risk for Transmission and Older Age

  1. Mar Masiá
  2. Marta Fernández-González
  3. Manuel Sánchez
  4. Mar Carvajal
  5. José Alberto García
  6. Nieves Gonzalo-Jiménez
  7. Victoria Ortiz de la Tabla
  8. Vanesa Agulló
  9. Inmaculada Candela
  10. Jorge Guijarro
  11. José Antonio Gutiérrez
  12. Carlos de Gregorio
  13. Félix Gutiérrez

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Abstract

Background

Performance of point-of-care tests in different clinical scenarios and on different samples remains undetermined. We comprehensively evaluated the performance of the nasopharyngeal Panbio COVID-19 Ag Rapid Test Device.

Methods

This is a prospective study that includes consecutive patients attending 3 primary care centers (PCCs) and an emergency department. The antigen test was performed at point-of-care in nasopharyngeal and nasal swabs and in saliva. Positive percent agreement (PPA) and negative percent agreement (NPA) were calculated with the reverse-transcription polymerase chain reaction (RT-PCR) assay as reference standard.

Results

Of 913 patients included, 296 (32.3%) were asymptomatic and 690 (75.6%) came from the PCC. Nasopharyngeal swabs were collected from 913 patients, nasal swabs were collected from 659 patients, and saliva was collected from 611 patients. The RT-PCR was positive in 196 (21.5%) nasopharyngeal samples (NPS). Overall, PPA (95% CI) in NPS was 60.5% (53.3–67.4), and it was lower in nasal swabs (44.7%) and saliva (23.1%). Test performance in NPS was largely dependent on the cycle threshold (Ct) in RT-PCR, with PPA of 94% for Ct ≤25 and 80% for Ct <30. In symptomatic patients, the PPA was 95% for Ct ≤25, 85% for Ct <30, and 89% for the symptom triad of fever, cough, and malaise. Performance was also dependent on age, with a PPA of 100% in symptomatic patients >50 years with Ct <25. In asymptomatic patients, the PPA was 86% for Ct <25. In all cases, NPA was 100%.

Conclusions

The nasopharyngeal Panbio COVID-19 Ag test performed at point-of-care has a good sensitivity in symptomatic patients with Ct <30 and older age. The test was useful to identify asymptomatic patients with lower Ct values.

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  1. Version published to 10.1093/ofid/ofab059
  2. ScreenIT

    SciScore for 10.1101/2020.11.16.20230003: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementConsent: Informed consent was obtained from all patients, and the study was approved by the Hospital General Universitario de Elche COVID-19 Institutional Advisory Board.
    IRB: Informed consent was obtained from all patients, and the study was approved by the Hospital General Universitario de Elche COVID-19 Institutional Advisory Board.
    Randomizationnot detected.
    Blindingnot detected.
    Power AnalysisThe estimated sample size for a sensitivity of at least 91.4% (according to the manufacturer), a precision of 2.5% and a statistical power of 80%, was 762 patients.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Limitations of the study include the lack of statistical power for the analysis of the test performance in specific subgroups, and the incomplete information about number of days since the risk contact in asymptomatic patients. Strengths are the real-life conditions in which the antigen test has been used to assess its true performance, the inclusion of consecutive unselected patients which allowed analyzing how it performs in diverse clinical scenarios, and the on-site execution of the test. In conclusion, the sensitivity of the nasopharyngeal Panbio COVID-19 antigen RDT is closely related to the Ct values, age and the presence and duration of symptoms. The test performance is optimal in symptomatic patients older than 50 years with viral loads linked with infectivity, and in asymptomatic patients the test may be useful to identify those with a higher risk for transmission. The saliva is not a suitable alternative sample for antigen detection.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.11.16.20230003 on medRxiv