Performance of the 2017 American College of Rheumatology/European League Against Rheumatism Provisional Classification Criteria for Antineutrophil Cytoplasmic Antibody-Associated Vasculitis in a Peruvian Tertiary Care Center

Aim To validate the new classification criteria for antineutrophil cytoplasmic antibody-associated vasculitis in a real-life Peruvian cohort of antineutrophil cytoplasmic antibody-associated vasculitis patients. Methods We reviewed medical records from a Peruvian tertiary care center from January 1990 to December 2019. Antineutrophil cytoplasmic antibody-associated vasculitis was diagnosed based on the 1990 American College of Rheumatology (ACR) criteria, the 2012 Chapel Hill Consensus Conference definitions, the European Medicines Agency (EMEA) algorithm, and the clinical acumen of the treating rheumatologists. We classified all patients using the "former criteria"(the 1990 ACR criteria for granulomatosis with polyangiitis [GPA] and eosinophilic GPA [EGPA] and the 1994 Chapel Hill Consensus Conference definition for microscopic polyangiitis [MPA]), the EMEA algorithm, and the "new criteria"(the 2017 ACR/European League Against Rheumatism Provisional Criteria). The level of agreement (using Cohen κ) was calculated using the clinical diagnosis as the criterion standard. Results We identified 212 patients, 12 of whom were excluded. One hundred fifty-four (77%) had MPA, 41 (20.5%) GPA, and 5 (2.5%) EGPA. The new criteria performed well for MPA (κ = 0.713) and EGPA (κ = 0.659), whereas the EMEA algorithm performed well for GPA (κ = 0.938). In the overall population, the new criteria showed better agreement (κ = 0.653) than the EMEA algorithm (κ = 0.506) and the former criteria (κ = 0.305). Conclusions The 2017 ACR/European League Against Rheumatism Provisional Criteria showed better agreement for the clinical diagnosis of all the patients overall and had the best performance for MPA and EGPA. The EMEA algorithm had the best performance for GPA.