Remission and Low-Disease Activity in Granulomatosis with Polyangiitis and Microscopic Polyangiitis: Prevalence and Impact on Damage Accrual

Objective: To assess the prevalence and impact on damage accrual of different levels of disease activity in patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). Methods: Patients with GPA and MPA followed for ≥5 years in 2 different centers were included. Disease activity and damage were assessed using the Birmingham Vasculitis Activity Score (BVAS) and Vasculitis Damage Index (VDI), respectively. Three levels of remission were defined: complete remission (BVAS = 0, negative for antineutrophil cytoplasmic antibody [ANCA], off treatment), clinical remission off therapy (CROffT; BVAS = 0, positive for ANCA), and clinical remission on therapy (CROnT; BVAS = 0, negative or positive for ANCA, glucocorticoids ≤5 mg/day and/or immunosuppressant). A low disease activity state (LDAS) was defined as 0 < BVAS ≤3, low-dose glucocorticoids (≤7.5 mg/day), and/or immunosuppressant. Remission or LDAS were defined as prolonged when lasting ≥2 consecutive years. Results: A total of 167 patients were included: 128 (76.6%) with GPA, 39 (23.4%) with MPA, mean ± SD age 51.0 ± 16.7 years. During a 5-year follow-up, 10 patients (6.0%) achieved prolonged complete remission, 6 (3.6%) prolonged CROffT, 89 (53.3%) prolonged CROnT, 42 (25.1%) prolonged LDAS, and 20 (12.0%) never achieved LDAS. The VDI score at 5 years progressively worsened according to increasing levels of disease activity targets (complete remission, CROffT, CROnT, and LDAS). The mean ± SD 5-year VDI score was higher in patients not achieving prolonged remission compared to those who did (3.7 ± 2.0 versus 2.2 ± 1.9; P < 0.0001). By multivariate analysis, baseline ear, nose, and throat (P = 0.006), and lung involvement (P = 0.047) were negative predictors of prolonged remission. Conclusion: More than 60% of patients with GPA/MPA achieved prolonged remission, which was associated with better long-term outcomes. In contrast, prolonged LDAS correlated with increased damage accrual and was not a sufficient treatment target.