EUH Resident Report: What are the sensitivity/specificity for ANCA and other auto-immune panels for Churg-Strauss syndrome?

The Bottom Line: In 1990, the American College of Rheumatology (ACR) defined the classification criteria to distinguish between the different vasculitides and identified six criteria for EGPA, namely asthma, eosinophilia >10%, neuropathy, non-fixed lung infiltrates, paranasal sinus abnormalities and extravascular eosinophils on biopsy. When four or more of these criteria are met, vasculitis can be classified as EGPA with a sensitivity of 85% and a specificity of 99.7% (Greco et al, 2015).

NCA testing by IIF has a higher sensitivity compared with ELISA, which has higher specificity for the diagnosis of ANCA-associated vasculitis. In a cross-sectional study, the overall sensitivity for IIF testing alone was 67% and specificity was 93%; for ELISA alone, overall sensitivity was 55% and specificity was 96%; and for combined IIF and ELISA, overall sensitivity was 52% and specificity was 99% for ANCA-associated vasculitis (Bui & Kermani, 2016).

References: Bui VL, Kermani TA. Clinical significance of a positive antineutrophil cytoplasmic antibody (ANCA) test. JAMA. 2016 Sept 6; 316(9):984-985. doi:10.1001/jama.2016.8307.

Greco A, Rizzo MI, Di Virgilio A, et al. Churg-Strauss syndrome. Autoimmunity Reviews. 2015 Apr; 15(4):341-348. doi: 10.1016/j.autrev.2014.12.004.

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