Prevalence Threshold and Temporal Interpretation of Screening Tests: The Example of the SARS-CoV-2 (COVID-19) Pandemic

  1. Jacques Balayla
  2. Ariane Lasry
  3. Yaron Gil
  4. Alexander Volodarsky-Perel

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Abstract

The curvilinear relationship between a screening test's positive predictive value (PPV) and its target disease prevalence is proportional. In consequence, there is an inflection point of maximum curvature in the screening curve defined as a function of the sensitivity and specificity beyond which the rate of change of a test's PPV declines sharply relative to disease prevalence. Herein, we demonstrate a mathematical model exploring this phenomenon and define the prevalence threshold point where this change occurs. Understanding where this prevalence point lies in the curve has important implications for the interpretation of test results, the administration of healthcare systems, the implementation of public health measures, and in cases of pandemics like SARS-CoV-2, the functioning of society at large. To illustrate the methods herein described, we provide the example of the screening strategies used in the SARS-CoV-2 (COVID-19) pandemic, and calculate the prevalence threshold statistic of different tests available today. This concept can help contextualize the validity of a screening test in real time, thereby enhancing our understanding of the dynamics of the current pandemic.

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    SciScore for 10.1101/2020.05.17.20104927: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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

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  2. Version published to 10.1101/2020.05.17.20104927v1 on medRxiv