113. PERFORMANCE OF ACR/EULAR PROVISIONAL CLASSIFICATION CRITERIA FOR ANCA-ASSOCIATED VASCULITIS (AVV) IN SOUTH AMERICAN PATIENTS Free

Background: AAV are necrotizing primary vasculitis with multisystemic manifestations of unknown etiology including: Microscopic Polyangiitis (MPA), Granulomatosis with Polyangiitis (GPA), Eosinophilic Granulomatosis with Polyangiitis (EGPA). There are no diagnostic criteria for AAV. Currently the DCVAS (Diagnosis and Classification Criteria in Vasculitis) project is developing diagnostic criteria for AAV, using data-driven methods. Our objective was to evaluate and compare the accuracy of ACR/EULAR provisional Classification Criteria for GPA, MPA and EGPA with the ACR 1990 Classification Criteria in a cohort of patients from a country in South America.

Methods: All adult patients with diagnoses of AAV according to their rheumatologist judgment, from 2000–2018 at the Hospital Clínico de la Universidad de Chile and Clínica Alemana de Santiago of Chile were included. Clinical variables were extracted form medical chart and AAV database. Based on that data, the Classification criteria ACR 1990, for GPA and EGPA; and preliminary ACR/EULAR (DCVAS) classification criteria for GPA, MPA and EGPA were applied. The values for sensitivity (SE), specificity (SP), positive predictive value. (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR) and accuracy were calculated.

Results: From 108 patients, there were 59 GPA (54% female, mean age 53 [27-80] y.o.), 39 MPA (72% female, mean age 63 [32-85] y.o.) and 10 EGPA (30% female, mean age 36 [21-53] y.o.). From GPA cases, 33 (55.9%) fulfilled the GPA ACR 1990 criteria and 48 (81.3%) GPA ACR/EULAR criteria. From the patients diagnosed as having MPA 38 (97.4%) fulfilled MPA ACR/EULAR criteria. From the 10 patients with EGPA, 5 (50.0%) fulfilled EGPA ACR criteria and 9 (90.0%) for EGPA ACR/EULAR criteria. The diagnostic performance characteristics and accuracy are shown in the table.

Conclusion: In South American patients, provisional ACR/EULAR criteria for diagnosis and classification of GPA, MPA and EGPA have good accuracy. The diagnostic accuracy for GPA and EGPA was better than ACR 1990 classification criteria.

Disclosures: None