Clinical characteristics of and risk factors for serious infection in Japanese patients within six months of remission induction therapy for antineutrophil cytoplasmic antibody-associated vasculitis registered in a nationwide, prospective, inception cohort study

Objectives: The purpose of this study was to identify the clinical characteristics and predictors of serious infections (SIs) in the RemIT-JAV, a nationwide, prospective, inception cohort study for Japanese patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Methods: We analyzed SIs within six months of remission induction therapy in 156 AAV patients. Hazard ratios with 95% confidence intervals (CIs) for SIs were calculated using the COX proportional hazard model. Results: Sixty-three SIs in 42 patients were identified. The incidence rate (IR) of SIs was 87.59/100 patient-years. The median length of time to the onset of first SIs was 54 days. Hazard ratios (95%CI) for SIs were 1.97 (0.99-3.95) for age >65 years, 0.47 (0.25-0.89) for female sex, 2.11 (1.05-4.27) for the severe form of AAV, and 2.88 (1.49-5.88) for initial PSL >0.8 mg/kg/day in the first model, and 2.64 (1.39-5.01) for smoking and 3.27 (1.66-6.45) for initial PSL >0.8 mg/kg/day in the second model. Conclusions: Lowering the IR of SIs in Japanese AAV patients is mandatory to improve the vital prognosis of these patients. For remission induction therapy of AAV patients with these risk factors, risk management of immunosuppressive treatment should be carefully considered.