To evaluate the efficacy and safety of low-dose rituximab (LD-RTX) for remission induction in patients with ANCA-associated vasculitis (AAV).

Patients with AAV who received RTX between 2006 and 2025 at Chinese PLA General Hospital were retrospectively reviewed. Low-dose RTX was defined as either 500mg or 375mg/m² administered at day 0 and 14, while all other RTX regimens were categorized as non-standard doses. Baseline demographic, clinical, and laboratory data were collected. The primary outcome was remission at 6 months, defined as a Birmingham Vasculitis Activity Score (BVAS) of 0. Secondary outcomes included remission at 3 months, changes in ANCA titres, peripheral B-cell levels, and adverse events during follow-up. Efficacy analyses were performed in patients with evaluable follow-up data, and safety analyses included all RTX-treated patients.

A total of 87 patients were included. Baseline demographic, clinical, and laboratory characteristics were comparable between the two groups. At 3 months, remission was achieved in 32/43 (74.4%) patients in the LD-RTX group and 4/40 (10.0%) patients in the non-standard RTX (NS-RTX) group (P < 0.001). The corresponding remission rates at 6 months were 38/43 (88.4%) and 7/40 (17.5%), respectively (P < 0.001).Median ANCA titre decreased from 200.0 at baseline to negative by 6 months in the LD-RTX group, whereas it remained detectable at a median level of 37.5 in the NS-RTX group.Median B-cell level in the LD-RTX group decreased from 0.73% at baseline to 0.01% at 6 months; the corresponding values in the NS-RTX group were 0.12% and 0.03% respectively. Adverse events (AEs) occurred in 6/43 (13.9%) patients in the LD-RTX group and 11/40 (27.5%) patients in the NS-RTX group (P = 0.274).

Low-dose rituximab may represent an effective and well-tolerated option for remission induction in AAV in Chinese Population, with higher remission rates, more complete B-cell depletion, and lower ANCA titres than non-standard rituximab regimens.