Evaluation of PR3- and MPO-ANCA line and dot immunoassays in ANCA-associated vasculitis.

Abstract

This study was performed to evaluate the diagnostic accuracy of novel line and dot immunoassays for detection of MPO and PR3 ANCA. Sera from 50 patients with ANCA-associated vasculitis (AAV), including granulomatosis with polyangiitis and microscopic polyangiitis, and from 45 disease controls were tested by IIF and for the presence of PR3-ANCA and MPO-ANCA by four different line or dot immunoassays, as well as by a chemiluminescence immunoassay. The area under the curve of the receiver operating characteristic curve to discriminate AAV from controls was 0.858 (95% CI 0.785-0.931) for the IIF method. For the antigen-specific immunoassays, the area under the curve varied between 0.869 (95% CI 0.797-0.941) and 0.936 (95% 0.886-0.985). Our comparison of various ANCA detection methods showed a high degree of diagnostic precision for all of the PR3- and MPO-ANCA line and dot immunoassays investigated. The performance was equal to or better than the performance of IIF. These results indicate that novel line and dot immunoassays can serve as a first-line test method in patients with the suspected diagnosis of AAV.