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bioRxiv · 10.1101/2020.06.02.131144

SARS-CoV2 Testing: The Limit of Detection Matters

Arnaout, R.·Lee, R.·Lee, G. R.·Callahan, C.·Yen, C. F.·Smith, K. P.·Arora, R.·Kirby, J. E.
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Abstract

Resolving the COVID-19 pandemic requires diagnostic testing to determine which individuals are infected and which are not. The current gold standard is to perform RT-PCR on nasopharyngeal samples. Best-in-class assays demonstrate a limit of detection (LoD) of ~100 copies of viral RNA per milliliter of transport media. However, LoDs of currently approved assays vary over 10,000-fold. Assays with higher LoDs will miss more infected patients, resulting in more false negatives. However, the false-negative rate for a given LoD remains unknown. Here we address this question using over 27,500 test results for patients from across our healthcare network tested using the Abbott RealTime SARS-CoV-2 EUA. These results suggest that each 10-fold increase in LoD is expected to increase the false negative rate by 13%, missing an additional one in eight infected patients. The highest LoDs on the market will miss a majority of infected patients, with false negative rates as high as 70%. These results suggest that choice of assay has meaningful clinical and epidemiological consequences. The limit of detection matters.

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Arnaout, R., Lee, R., Lee, G. R., Callahan, C., Yen, C. F., Smith, K. P., Arora, R., Kirby, J. E.. 2020-06-04. SARS-CoV2 Testing: The Limit of Detection Matters. https://doi.org/10.1101/2020.06.02.131144

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