Preprint Article Version 3 Preserved in Portico This version is not peer-reviewed

“Clinician’s Probability Calculator” to Convert Pre-Test to Post-Test Probability of COVID-19, Based on Method Validation from Each Laboratory

Version 1 : Received: 2 December 2020 / Approved: 4 December 2020 / Online: 4 December 2020 (09:03:51 CET)
Version 2 : Received: 4 January 2021 / Approved: 4 January 2021 / Online: 4 January 2021 (16:39:23 CET)
Version 3 : Received: 1 March 2021 / Approved: 3 March 2021 / Online: 3 March 2021 (10:08:27 CET)

How to cite: Brooks, Z.; Das, S.; Pliura, T. “Clinician’s Probability Calculator” to Convert Pre-Test to Post-Test Probability of COVID-19, Based on Method Validation from Each Laboratory. Preprints 2020, 2020120094 (doi: 10.20944/preprints202012.0094.v3). Brooks, Z.; Das, S.; Pliura, T. “Clinician’s Probability Calculator” to Convert Pre-Test to Post-Test Probability of COVID-19, Based on Method Validation from Each Laboratory. Preprints 2020, 2020120094 (doi: 10.20944/preprints202012.0094.v3).

Abstract

Identifying the SARS-CoV-2 virus has been a unique challenge for the scientific community. In this paper, we discuss a practical solution to help guide clinicians with interpretation of the probability that a positive, or negative, COVID-19 test result indicates an infected person, based on their clinical estimate of pre-test probability of infection.The authors conducted a small survey on LinkedIn to confirm that hypothesis that that the clinical pre-test probability of COVID-19 increases relative to local prevalence of disease plus patient age, known contact, and severity of symptoms. We examined results of PPA (Positive Percent Agreement, sensitivity) and NPA (Negative Percent Agreement, specificity) from 73 individual laboratory experiments for molecular tests for SARS-CoV-2 as reported to the FIND database 1, and for selected methods in FDA EUA submissions2,3. Authors calculated likelihood ratios to convert pre-test to post-test probability of disease and designed an online calculator to create graphics and text to report results. Despite best efforts, false positive and false negative Covid-19 test results are unavoidable4,5. A positive or negative test result from one laboratory has a different probability for the presence of disease than the same result from another laboratory. Likelihood ratios and confidence intervals can convert the physician or other healthcare professional’s clinical estimate of pre-test probability to post-test probability of disease. Ranges of probabilities differ depending on proven method PPA and NPA in each laboratory. We recommend that laboratories verify PPA and NPA and utilize a the “Clinician’s Probability Calculator” to verify acceptable test performance and create reports to help guide clinicians with estimation of post-test probability of COVID-19.

Supplementary and Associated Material

https://vimeo.com/517630987: Pre-Test to Post-test Probability

Subject Areas

COVID-19; SARS-COV-2; False-Positive; False-Negative; Likelihood Ratio; Probability; Calculator; Interpretation

Comments (1)

Comment 1
Received: 3 March 2021
Commenter: Zoe Brooks
Commenter's Conflict of Interests: Author
Comment: In this version, the tables are simplified.  The survey of opinion of clinical pre-test probability is replaced with literature references.  A video is added to guide people through key concepts and case studies.
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