Evaluation of the rapid Quidel Sofia Lyme fluorescent immunoassay as a first-tier test in a modified 2-tier testing algorithm for Lyme disease: A comparison with the Zeus ELISA Borrelia VlsE1/pepC10 lgG/IgM assay followed by the Zeus monovalent IgM/IgG confirmatory assay

Recently modified 2-tier testing (MTTT) algorithms using 2 enzyme immunoassays (EIAs) as opposed to an EIA followed by immunoblot have been approved by the US Food and Drug Administration (FDA) for the screening and confirmation of Lyme disease. The Quidel Sofia Lyme fluorescent immunoassay is a rapid lateral-flow method that can be performed in real time, permitting on-demand testing. We evaluated the performance of the Sofia assay as a first-tier test in an MTTT algorithm.We compared the Sofia Lyme test with the Zeus ELISA Borrelia VlsE1/pepC10 lgG/IgM test, followed by the Zeus monovalent IgM/IgG EIA as the confirmatory test.When used as a first-tier test compared with a standard Zeus MTTT assay, the positive percentage agreement was 91.4%% (95% CI, 77.6%-97.0%). The negative percentage agreement was 100% (95% CI, 94.0%-100%). The overall agreement was 98.3% (95% CI, 94.2%-99.4%). κ = 0.945, indicating "almost perfect agreement."The Sofia Lyme test performs well compared with an FDA-approved MTTT.