Characteristics of Three Different Chemiluminescence Assays for Testing for SARS-CoV-2 Antibodies

  1. Myriam C. Weber
  2. Martin Risch
  3. Sarah L. Thiel
  4. Kirsten Grossmann
  5. Susanne Nigg
  6. Nadia Wohlwend
  7. Thomas Lung
  8. Dorothea Hillmann
  9. Michael Ritzler
  10. Francesca Ferrara
  11. Susanna Bigler
  12. Konrad Egli
  13. Thomas Bodmer
  14. Mauro Imperiali
  15. Yacir Salimi
  16. Felix Fleisch
  17. Alexia Cusini
  18. Sonja Heer
  19. Harald Renz
  20. Matthias Paprotny
  21. Philipp Kohler
  22. Pietro Vernazza
  23. Lorenz Risch
  24. Christian R. Kahlert

Reviewed by

Read the full article

Listed in

Log in to save this article

Abstract

Several tests based on chemiluminescence immunoassay techniques have become available to test for SARS-CoV-2 antibodies. There is currently insufficient data on serology assay performance beyond 35 days after symptoms onset. We aimed to evaluate SARS-CoV-2 antibody tests on three widely used platforms. A chemiluminescent microparticle immunoassay (CMIA; Abbott Diagnostics, USA), a luminescence immunoassay (LIA; Diasorin, Italy), and an electrochemiluminescence immunoassay (ECLIA; Roche Diagnostics, Switzerland) were investigated. In a multigroup study, sensitivity was assessed in a group of participants with confirmed SARS-CoV-2 ( n = 145 ), whereas specificity was determined in two groups of participants without evidence of COVID-19 (i.e., healthy blood donors, n = 191 , and healthcare workers, n = 1002 ). Receiver operating characteristic (ROC) curves, multilevel likelihood ratios (LR), and positive (PPV) and negative (NPV) predictive values were characterized. Finally, analytical specificity was characterized in samples with evidence of the Epstein–Barr virus (EBV) ( n = 9 ), cytomegalovirus (CMV) ( n = 7 ), and endemic common-cold coronavirus infections ( n = 12 ) taken prior to the current SARS-CoV-2 pandemic. The diagnostic accuracy was comparable in all three assays (AUC 0.98). Using the manufacturers’ cut-offs, the sensitivities were 90%, 95% confidence interval [84,94] (LIA), 93% [88,96] (CMIA), and 96% [91,98] (ECLIA). The specificities were 99.5% [98.9,99.8] (CMIA), 99.7% [99.3,99.9] (LIA), and 99.9% [99.5,99.98] (ECLIA). The LR at half of the manufacturers’ cut-offs were 60 (CMIA), 82 (LIA), and 575 (ECLIA) for positive and 0.043 (CMIA) and 0.035 (LIA, ECLIA) for negative results. ECLIA had higher PPV at low pretest probabilities than CMIA and LIA. No interference with EBV or CMV infection was observed, whereas endemic coronavirus in some cases provided signals in LIA and/or CMIA. Although the diagnostic accuracy of the three investigated assays is comparable, their performance in low-prevalence settings is different. Introducing gray zones at half of the manufacturers’ cut-offs is suggested, especially for orthogonal testing approaches that use a second assay for confirmation.

Article activity feed

  1. Version published to 10.1155/2021/8810196
  2. ScreenIT

    SciScore for 10.1101/2020.11.05.20225003: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study protocol was verified by the cantonal ethics boards of Zurich (BASEC Req-20-00587) and Eastern Switzerland (EKOS; BASEC Nr.
    Consent: Whereas the cohort with healthcare workers provided written informed consent, informed consent for performing laboratory analysis on anonymized samples in the other three groups was waived.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The patients from Liechtenstein were prospectively and consecutively enrolled within a national COVID-19 cohort, whereas the Swiss patients consisted from a retrospectively assembled convenience sample, both detailed in references 37,38, The second group of individuals was prospectively assembled and consisted of consecutive healthy blood donors from the Blutspendedienst Graubünden without clinical suspicion of COVID-19 providing blood for testing SARS-CoV2 antibodies from April 15th to May 4th, 2020 (n=191).
    SARS-CoV2
    suggested: None
    Such an orthogonal testing approach for SARS-CoV-2 antibodies has been reported to have a very high positive predictive value for COVID-19 and therefore is suited to reliably exclude individuals with recent COVID-19 infection 40-42.
    SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    The antibodies were tested on the following diagnostic platforms: COBAS 6000 (Roche Diagnostics, Rotkreuz, Switzerland), Abbott Architect i2000 (Abbott Diagnostics Baar, Switzerland), and Liaison XL (Diasorin, Luzern, Switzerland).
    Abbott Architect
    suggested: (Abbott ARCHITECT i1000sr System, RRID:SCR_019328)
    Abbott
    suggested: (Abbott, RRID:SCR_010477)
    Medcalc version 18.11.3 (Mariakerke, Belgium) and Microsoft Excel 2016 MSO (16.0.8431.2046) (Microsoft Inc, Seattle, USA) were used for statistical and graphical computations.
    Medcalc
    suggested: (MedCalc, RRID:SCR_015044)
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)

    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:
    Our study has strengths and limitations. A strength is that specificity has been assessed in a large group of 1193 individuals without evidence of COVID-19. Such an approach offers the possibility to describe the specificity with relatively narrow confidence intervals. A further strength is that we investigate several potential cut-offs for clinical decision making. A limitation of the study is that samples employed for evaluation of specificity were selected from contemporary and not pre-pandemic participants. Two positive serology results in an orthogonal testing approach cannot provide 100% certainty that any remaining false positives are truly false positive. Nevertheless, we demonstrate that combination of two positive results with chemiluminescence assays has a very high positive predictive value even at low pretest probabilities, comparable to that known from molecular methods 42. Further, inclusion of the index serology tests as part of the reference standard definition of absence of disease carries a risk of bias in results. At low pretest probabilities, such a bias might have a considerable impact on positive predictive values. There are several factors mitigating such a misinterpretation: a.) utilizing an orthogonal testing approach in initially positive results, b.) the fact that even in the first wave of COVID-19, COVID-19 prevalence in some regions of Europe was already more than 10%, which cannot be considered low 50. The specificities identified in our study f...

    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 10.1101/2020.11.05.20225003 on medRxiv