Reclassification of previously diagnosed GPA patients using the 2022 ACR/EULAR classification criteria

This study applied the 2022 criteria for granulomatosis with polyangiitis (GPA) proposed by the ACR and EULAR (the 2022 ACR/EULAR criteria) to Korean patients with previously diagnosed GPA to investigate the number of patients who could be reclassified as having GPA.

Sixty-five patients with GPA, who met the 2012 revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides and the 2007 European Medicines Agency algorithm for GPA, were included in this study. They were reclassified based on the 2022 ACR/EULAR criteria.

Of the 65 patients, 48 patients (73.8%) were reclassified as having GPA. A patient could not be reclassified as having GPA if the patient did not have a total score of 5 despite granulomas on biopsy or clear GPA surrogate markers. Among the 17 patients unclassified as having GPA, 16 patients were reclassified as having MPA and one as having unclassifiable vasculitis, and furthermore, 94.1% of them harboured MPO-ANCA (or perinuclear (P)-ANCA).

The concordance rate between the 2022 ACR/EULAR criteria for GPA and the previous criteria in patients with previously diagnosed GPA was 73.8%. Although the 2022 ACR/EULAR criteria are the product of the most advanced methodologic process, it should be noted that there were some consequences of distorting the CHCC definition, and further discussion is required, especially with respect to the weightage of the items.