iDart Lyme IgM ImmunoBlot Kit

The iDart Lyme IgM ImmunoBlot Kit is an in vitro diagnostic immunoblot assay that detects IgM antibodies to Borrelia burgdorferi in human serum to aid in diagnosing Lyme disease. It uses recombinant antigenic proteins applied as discrete lines on a nitrocellulose membrane and is intended for symptomatic patients with clinical signs and symptoms consistent with Lyme disease, not for screening asymptomatic individuals.

The device employs a line blot immunoassay format with manual result interpretation, detecting IgM antibodies against specific B. burgdorferi antigens (LSA, P41, P39, P23, P31, P34, C10, and 93 kD protein). The predicate uses a microarray format with automated reader technology. Both use serum specimens and include positive and negative controls, but differ in assay platform and result generation methodology.

The applicant referenced the FDA guidance document 'Establishing the Performance Characteristics of In Vitro Diagnostic Devices for the Detection of Antibodies to Borrelia burgdorferi' (March 2013).

The device is substantially equivalent because it targets the same measurand (IgM antibodies to B. burgdorferi) using a qualitative immunoassay format on serum specimens with identical intended use and patient population restrictions as the predicate. Although the technical platform differs (line blot vs. microarray), the clinical performance is comparable: the device achieved 90.91% positive percent agreement and 98.07% negative percent agreement against the standard two-tier test methodology across 997 clinical samples, with high reproducibility (100% agreement across three sites and multiple operators) and appropriate analytical specificity (99.44% in endemic populations, 97.94% against cross-reactive pathogens).