ANCA-associated scleritis: impact of ANCA on presentation, response to therapy and outcome

Objectives To describe the characteristics, treatment and outcome of isolated ANCA-associated scleritis at diagnosis compared with idiopathic scleritis with negative ANCA tests. Methods This retrospective multicentre case-control study was performed within the French Vasculitis Study Group (FVSG) network and in three French tertiary ophthalmologic centres. Data from patients with scleritis without any systemic manifestation and with positive ANCA results were compared with those of a control group of patients with idiopathic scleritis with negative ANCA tests. Results A total of 120 patients, including 38 patients with ANCA-associated scleritis and 82 control patients, diagnosed between January 2007 and April 2022 were included. The median follow-up was 28 months (IQR 10-60). The median age at diagnosis was 48 years (IQR 33-60) and 75% were females. Scleromalacia was more frequent in ANCA-positive patients (P = 0.027) and 54% had associated ophthalmologic manifestations, without significant differences. ANCA-associated scleritis more frequently required systemic medications, including glucocorticoids (76% vs 34%; P < 0.001), and rituximab (P = 0.03) and had a lower remission rate after the first- and second-line treatment. Systemic ANCA-associated vasculitis (AAV) occurred in 30.7% of patients with PR3- or MPO-ANCA, after a median interval of 30 months (IQR 16.3-44). Increased CRP >5 mg/l at diagnosis was the only significant risk factor of progression to systemic AAV [adjusted hazard ratio 5.85 (95% CI 1.10, 31.01), P = 0.038]. Conclusion Isolated ANCA-associated scleritis is mostly anterior scleritis with a higher risk of scleromalacia than ANCA-negative idiopathic scleritis and is more often difficult to treat. One-third of patients with PR3- or MPO-ANCA scleritis progressed to systemic AAV.