Resource: FDA COVID-19 Testing Update
Source: U.S. Food and Drug Administration
Synopsis: The FDA released several important data compilation tables of the molecular PCR testing. This is comparative data of the different manufacturers and their corresponding molecular PCR tests. Using the limit of detection (LoD) value as the primary value to rate the tests. In other words, the lower the value of the LoD, the higher the sensitivity. For example the Abbott Molecular Company has a PCR test called the Abbott RealTime SARS-CoV-2 assay which has LoD of 5,400. This favorably compares to the Cepheid Company PCR test called the Xpert Xpress SARS-CoV-2 test which has an LoD of 5,400 as well. These two tests are distributed nationwide and are amongst the most frequently used tests on the market. The lowest LoD is 180 from PerkinElmer. The highest LoD is 600,000 from Boston Medical Center. Limit of detection matters. Assays with higher LoD will miss more infected patients, resulting in more false negatives. For each 10 fold increase in LoD there is an expected increase in the false negative rate by 13%. The highest LoD on the market will miss a majority of infected patients, with false negative rates as high as 70%. Therefore the choice of assay has meaningful clinical and epidemiological consequences.
Comments: It is definitely worthwhile to review this article and read table 1 and table 2. For example, if you’re thinking of buying an Abbott ID NOW machine for $4,500, you can compare it to other testing machines and the LoD with other machines currently on the market.
