Risk factors for infectious complications of ANCA-associated vasculitis: a cohort study.

Background: Severe infections are common complications of immunosuppressive treatment for antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with renal involvement. We investigated the clinical characteristics and risk factors of severe infection in Chinese patients with AAV after immunosuppressive therapy.

Methods: A total of 248 patients with a new diagnosis of ANCA-associated vasculitis were included in this study. The incidence, time, site, and risk factors of severe infection by the induction therapies were analysed. Multivariate Cox proportional hazards models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CI).

Results: A total of 103 episodes of severe infection were identified in 86 (34.7%, 86/248) patients during a median follow-up of 15 months. The incidence of infection during induction therapy was 38.5% for corticosteroids (CS), 39.0% for CS+ intravenous cyclophosphamide (IV-CYC), 33.8% for CS+ mycophenolate mofetil and 22.5% for CS + tripterygium glycosides, 76 (73.8%) infection episodes occurred within 6 months, while 66 (64.1%) occurred within 3 months. Pneumonia (71.8%, 74/103) was the most frequent type of infection, and the main pathogenic spectrum included bacteria (78.6%), fungi (12.6%), and viruses (8.7%). The risk factors associated with infection were age at the time of diagnosis (HR = 1.003, 95% CI = 1.000-1.006), smoking (HR = 2.338, 95% CI = 1.236-4.424), baseline secrum creatinine (SCr) ≥5.74 mg/dl (HR = 2.153, 95% CI = 1.323-3.502), CD4 T cell< 281 μl (HR = 1.813, 95% CI = 1.133-2.900), and intravenous cyclophosphamide regimen (HR = 1.951, 95% CI =1.520-2.740). Twelve (13.9%) patients died of severe pneumonia.

Conclusion: The infection rate during induction therapy was high in patients with AAV. Bacterial pneumonia was the main type of infection encountered. Age at the time of diagnosis, smoking, baseline SCr ≥5.74 mg/dl, CD4 T cell< 281 μl, and IV-CYC therapy were identified as risk factors for infection.