Reappraisal of Renal Arteritis in ANCA-associated Vasculitis: Clinical Characteristics, Pathology, and Outcome
Idris Boudhabhay, Florence Delestre, Guillaume Coutance, Viviane Gnemmi, T. Quéméneur, C. Vandenbussche, Hélène Lazareth, Guillaume Canaud, Leïla Tricot, Clément Gosset, Aurélie Hummel, Benjamin Terrier, Marion Rabant, Emma van Daalen, Maria A.C. Wester Trejo, Ingeborg M. Bajema, Alexandre Karras, Jean–Paul Duong Van Huyen
Abstract
Significance Statement The clinical significance of arteritis of the small kidney arteries has not been evaluated in detail in antineutrophil cytoplasmic antibody–associated vasculitis (AAV). A large multicenter cohort of 251 patients diagnosed with AAV and renal involvement, including 34 (13.5%) patients with arteritis, found patients with arteritis were older and had a more severe inflammatory syndrome compared with patients who did not have arteritis. The presence of arteritis on kidney biopsy was associated with poorer renal prognosis, independent of current risk stratification predictive models. The addition of the arteritis status significantly improved risk stratification of ESKD in patients classified as having low or moderate risk according to the ANCA renal risk score. The incidence and phenotype of this AAV subtype were confirmed in two external validation cohorts. Background Renal involvement in ANCA–associated vasculitis (AAV) is associated with poor outcomes. The clinical significance of arteritis of the small kidney arteries has not been evaluated in detail. Methods In a multicenter cohort of patients with AAV and renal involvement, we sought to describe the clinicopathologic characteristics of patients with AAV who had renal arteritis at diagnosis, and to retrospectively analyze their prognostic value. Results We included 251 patients diagnosed with AAV and renal involvement between 2000 and 2019, including 34 patients (13.5%) with arteritis. Patients with AAV-associated arteritis were older, and had a more pronounced inflammatory syndrome compared with patients without arteritis; they also had significantly lower renal survival ( P =0.01). In multivariable analysis, the ANCA renal risk score, age at diagnosis, history of diabetes mellitus, and arteritis on index kidney biopsy were independently associated with ESKD. The addition of the arteritis status significantly improved the discrimination of the ANCA renal risk score, with a concordance index (C-index) of 0.77 for the ANCA renal risk score alone, versus a C-index of 0.80 for the ANCA renal risk score plus arteritis status ( P =0.008); ESKD-free survival was significantly worse for patients with an arteritis involving small arteries who were classified as having low or moderate risk, according to the ANCA renal risk score. In two external validation cohorts, we confirmed the incidence and phenotype of this AAV subtype. Conclusions Our findings suggest AAV with renal arteritis represents a different subtype of AAV with specific clinical and histologic characteristics. The prognostic contribution of the arteritis status remains to be prospectively confirmed.