Usefulness of anti-dsDNA antibody screening with chemiluminescence followed by confirmation by indirect immunofluorescence.

Objective: The purpose of this study was to evaluate the performance of a chemiluminescent immunoassay (CLIA) to detect anti-dsDNA antibodies, using the indirect immunofluorescence test (IIF) on Crithidia luciliae as a reference.

Methods: The automation system demonstrated 81% efficiency, 100% sensitivity and 82% specificity according to the intrinsic validation process performed using 179 consecutive samples from 169 patients in the beginning of 2011. These patients were subsequently divided into 3 groups according to the co-reactivity of anti-dsDNA results using the 2 methods (reactive, non-reactive and discrepant results).

Results: Upon data analysis, 77% (129/169) of the tests were requested by rheumatologists, and 57% (97/169) of the samples were from lupus patients. Both the reactive and non-reactive results of the CLIA were well defined and standardised, and automation reduced the manual labor required by 70% in a safe and high-quality manner. Furthermore, the high prevalence of patients with lupus and nephritis among the CLIA false-positive results corroborates the hypothesis that the actual index of CLIA false positivity is lower than that initially found in this study.