Background Antineutrophilic cytoplasmic antibody (ANCA)-associated vasculitis (AAV) have overlapping manifestations. Classifications based on clinical criteria or ANCA specificity have emerged to individualize homogenized group of patients in terms of clinical forms and outcomes.

Objectives The aim of our study was to retrospectively re-evaluate the clinical impact and outcome of our monocentric AAV patients' cohort, according to classifications based on clinical criteria and/or ANCA specificity.

Methods A retrospective monocentric study carried out in Caen university hospital led to identify proteinase-3 (PR3) or myeloperoxidase (MPO)-ANCA AAV patients (via an ELISA technique), respectively from March 1997 to June 2016, and from September 2011 to June 2016. Patients with eosinophilic granulomatosis with polyangiitis were excluded. AAV were classified between granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA), and limited or severe forms according to respectively European Medicines Agency vasculitis algorithm and WGET group. Categorical variables were reported as percentages and compared using Chi² or Fisher's tests according to expected frequencies. Continuous variables were expressed as means and analyzed using Student's t-test. Associations between survival, or relapse free survival, and AAV classifications were evaluated by the log-rank test. A p-value <0.05 was considered to be statistically significant.

Results A total of 150 GPA/MPA were included.

As expected, ear-nose throat involvement were significantly higher in PR3-ANCA vs MPO-ANCA, and GPA vs MPA (p<0.001). Survival was significantly higher in anti-MPO GPA but relapse-free survival was lower, compared to anti-MPO MPA (p=0.038 and p=0.015, respectively), without difference in treatments. Relapse-free survival was lower in GPA, compared to MPA (p<0.001). Among GPA patients, there was significantly more deaths in PR3 than MPO patients (p=0.02), but without significant difference between ANCA types for all other considered criteria, including survival (p=0.06).

Conclusions The clinicopathological classification appeared as the strongest criteria for distinguish homogeneous forms and prognosis of AAV. Besides their diagnostic value, ANCA may not exhibited further great interest, especially in GPA.

Disclosure of Interest None declared