The American College of Rheumatology (ACR) and European Alliance of Associations for Rheumatology (EULAR) developed new criteria for the classification of patients with eosinophilic granulomatosis with polyangiitis (EGPA), according to a study published in Annals of the Rheumatic Diseases.
EGPA (formerly known as Churg-Strauss syndrome) is one of several types of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The ACR published classification criteria for EGPA in 1990; however, these criteria were not adequately validated.
This study outlines efforts by the ACR and EULAR to develop and validate classification criteria for distinguishing EGPA from similar types of vasculitis.
A steering committee of physicians, statisticians, and data managers directed the development and validation of the classification criteria. Using consensus methodology, a list of potential criteria items for systemic vasculitides was developed. These criteria items were collected from a cohort of patients with vasculitis who were enrolled internationally and then refined based on prevalence and clinical relevance in the cohort. Next, experts reviewed cases to establish a defined set of patients with AAV.
Finally, the AAV dataset was categorized into development and validation groups. In the development set, patients with EGPA were compared with patients with other types of AAV or vasculitis. Least absolute shrinkage and selection operator logistic regression were used to develop a points-based risk score for disease classification. The final classification criteria were then validated using the independent dataset.
The development and validation datasets included 107 and 119 patients with EGPA, respectively, and 450 and 437 comparator patients, respectively. More than 1000 candidate criteria items were initially proposed, which were narrowed down to 91 items through the consensus process and to 11 items through regression analysis, of which 7 were retained.
- Obstructive airway disease
- Nasal polyps
- Mononeuritis multiplex/motor neuropathy not due to radiculopathy
Laboratory and Biopsy Criteria
- Blood eosinophil count of 1 x 109/L or more
- Extravascular eosinophilic-predominant inflammation on biopsy
- Positive test for cytoplasmic ANCA or antiproteinase 3 (anti-PR3) antibodies
A score of 6 or higher indicated EGPA. In sensitivity analyses of the validation dataset, the sensitivity was 85% (95% CI, 77%-91%) and the specificity was 99% (95% CI, 98%-100%).
Limitations of the study included a relatively limited study population (ie, adult patients from North America, Europe, and Asia who were diagnosed with vasculitis) and a potential for referral bias. In addition, the criteria were intended to distinguish EGPA from other types of small- or medium-vessel vasculitis and are not appropriate for diagnosing EGPA.
The authors concluded, “The 2022 ACR/EULAR classification criteria for EGPA are the product of a rigorous methodological process that used an extensive data set generated by the work of a remarkable international group of collaborators. These criteria have been endorsed by the ACR and EULAR and are now ready for use to differentiate  type of vasculitis from another to define populations in research studies.”
Grayson PC, Ponte C, Suppiah R, et al. 2022 American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria for eosinophilic granulomatosis with polyangiitis. Ann. Rheum Dis. Published online Feburary 14, 2022. doi:10.1136/annrheumdis-2021- 221794