Testing for autoantibodies to extractable nuclear antigens (ENAs) plays an important role in the diagnosis and management of systemic rheumatic disease. Currently, no gold standard tests are available for detecting anti-ENAs. To address this gap, we aimed to identify an assay that exhibits satisfactory diagnostic performance in the detection of five common anti-ENAs by comparing two commonly used assays, an automated fluorescent enzyme immunoassay (FEIA) and a microplate ELISA assay.
Sera from 100 patients with systemic rheumatic disease were collected and assayed with FEIA and microplate ELISA to detect anti-ENAs. Statistical analyses were performed to check the agreement rate between the two platforms using kappa coefficients. Analytical sensitivity and specificity for each assay were calculated.
The concordance rates between ELISA and FEIA ranged from 89% for anti-RNP to 97% for anti-Scl-70, and the kappa coefficients of the two assays were in the range of 0.44 to 0.82. Between the two assays, a significant difference in sensitivity and specificity was seen only for anti-Sm and anti-RNP, respectively.
In this study, FEIA and ELISA showed comparable efficiency for detecting anti-ENAs.