2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for granulomatosis with polyangiitis

Objective: To develop and validate revised classification criteria for granulomatosis with polyangiitis (GPA).
Methods: Patients with vasculitis or comparator diseases were recruited into an international cohort. The study proceeded in five phases: i) Identification of candidate items using consensus methodology; ii) Prospective collection of candidate items present at time of diagnosis; iii) Data-driven reduction of candidate items; iv) Expert review to define the reference diagnosis; and v) Derivation of a points-based risk score for disease classification in a development set using lasso logistic regression with subsequent validation of performance characteristics in an independent set of cases and comparators.
Results: The development set for GPA consisted of 578 GPA cases and 652 comparators. The validation set consisted of an additional 146 cases of GPA and 161 comparators. From 91 candidate items, regression analysis identified 26 items for GPA, 10 of which were retained. The weighting of final criteria items was: i) Bloody nasal discharge, nasal crusting, or sino-nasal congestion (+3), ii) Cartilaginous involvement (+2), iii) Conductive or sensorineural hearing loss (+1), iv) cANCA or anti-PR3 ANCA positivity (+5), v) Pulmonary nodules, mass, or cavitation on chest imaging (+2), vi) Granuloma or giant cells on biopsy (+2), vii) Inflammation or consolidation of the nasal/paranasal sinuses on imaging (+1), viii) Pauci-immune glomerulonephritis (+1), ix) pANCA or anti-MPO ANCA positivity (-1), and x) Eosinophil count ≥ 1 (x109/L) (-4). After excluding mimics of vasculitis, a patient with a diagnosis of small- or medium-vessel vasculitis could be classified as GPA with a cumulative score of ≥ 5 points. When these criteria were tested in the validation dataset, the sensitivity was 93% (95% confidence interval [95% CI] 87-96%) and the specificity was 94% (95% CI 89-97%).
Conclusion: The 2020 ACR-EULAR GPA Classification Criteria demonstrate strong performance characteristics and are validated for use in research.