Yamaguchi M, et al. - Researchers performed a multicenter retrospective cohort study to determine the role of smoking as a risk factor for antineutrophil cytoplasmic antibody–associated small-vessel vasculitis relapse. Using multivariate Cox proportional hazards models, adjusted for clinically relevant factors, they assessed dose-response relationships between cigarette smoking and outcomes among 122 patients with granulomatosis with polyangiitis and microscopic polyangiitis (MPA) from 9 nephrology centers in Japan. Outcomes revealed that for relapse of MPA, smoking is a significant and dose-dependent risk factor. This emphasizes the significance of encouraging to quit smoke among all patients with MPA.