This study evaluated the diagnostic performance of the Pictor PictHealth® Immunoscreen ENA assay (a targeted proteomics, ELISA-format multiplex platform) for detecting extractable nuclear antigen (ENA) antibodies, comparing it against the Euroimmun ENA Line Immunoassay and BioPlex 2200 ENA assay using clinical sera from patients with autoimmune diseases.
Three-way concordance across all assays ranged from 67.3% (TRIM21/Ro52) to 100% (Jo-1), with Sm and CENP-B showing ~95% agreement. Pairwise positive percent agreement (PPA) and negative percent agreement (NPA) exceeded 85% for most autoantibodies.
Full text was inaccessible, so sample size, patient demographics, and detailed breakdown of pairwise PPA/NPA by analyte could not be verified. The comparator assays (Euroimmun LIA and BioPlex 2200) themselves lack a true gold standard, limiting definitive performance claims. TRIM21/Ro52 showed notably lower three-way concordance (67.3%), which may reflect known platform variability for this antigen.
The Pictor ENA assay performs comparably to established multiplex platforms for most ENA antibodies and may be a viable, lower-cost option for SARDs testing in resource-limited laboratories. Caution is warranted for TRIM21/Ro52 results, where concordance across platforms is lowest.
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