Influence of smoking on disease activity and prognosis of antineutrophil cytoplasmic antibody-associated vasculitis: a retrospective cohort study.

Abstract

Antineutrophil cytoplasmic antibody-associated vasculitides (AAV) are a group of autoimmune diseases characterized by inflammation of small blood vessels. Smoking is a potential trigger for such diseases, however, its link with AAV remains controversial. The aim of this study was to analyze the link between AAV and smoking based on clinical characteristics, disease activity, and mortality. This retrospective study included 223 AAV patients. Their smoking status was assessed at diagnosis and they were classified as ever smokers (ESs), including current or past smokers, and never smokers (NSs). Information regarding clinical presentation, the disease activity, immunosuppressive therapy, and survival was collected. The ESs had similar organ involvement to the NSs, except for significantly greater frequency of renal replacement therapy (31% vs 14%; P = 0.003). Median (interquartile range [IQR]) time from symptom onset to diagnosis was significantly shorter in the ESs than the NSs (4 [2-9.5] vs 6 [3-13] months; P = 0.03), with significantly higher mean (SD) value of the Birmingham Vasculitis Activity Score version 3 (19.5 [7.93] vs 17.25 [8.05]; P = 0.04). The ESs were more likely to receive cyclophosphamide therapy (P = 0.03), and had significantly higher morality than the NSs (hazard ratio, 2.89; 95% CI, 1.47-5.72; P = 0.002). There were no significant differences between the current and past smokers. The multivariable Cox proportional regression analysis found ever smoking and male sex to be independent predictors of mortality in AAV patients. Ever smoking is associated with increased AAV activity and more frequent renal replacement therapy and immunosuppressive treatment, resulting in a poorer survival prognosis in AAV patients. Future multicenter studies are required to further characterize the clinical, biological, and prognostic impact of smoking on AAV.