Severe infections in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis: a retrospective cohort study with a clinical phenotype approach.

Severe infections are common in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). We aimed to describe the characteristics of patients with AAV and severe infections according to clinical phenotype. Retrospective cohort study including patients with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). Baseline characteristics were compared between patients with and without at least one severe infection. Demographics, comorbidities, clinical characteristics, laboratory and treatment were retrieved at diagnosis and at every infectious event. One hundred and eight patients were included (57 with and 51 without infections). Patients with an infection had received more frequently methylprednisolone boluses at AAV diagnosis than patients without infections (OR 2.6, 95% CI 1.1-5.9, p = 0.01). There were a total of 108 severe infections in 57 patients (median follow-up 18 months). Thirty-two patients (56%) had an infectious complication within the first year of AAV diagnosis, 43 (75%) had pulmonary involvement during the first infection. The most frequent type of infection was pneumonia. Phenotypes were: Non-severe AAV (n = 11), severe PR3-AAV (n = 30), severe MPO-AAV (n = 9); the number of infectious events in each group was 11, 69, 18, respectively. Patients with severe MPO phenotype were older and required more frequently ICU stay compared to other phenotypes. Positive correlation was found between total of infections and pulmonary infiltrates due to vasculitis (ρ = 0.40, p = 0.003), endobronchial involvement (ρ = 0.40, p = 0.003), and alveolar hemorrhage (ρ = 0.34, p = 0.015). Severe infections, most commonly pneumonia, were frequent in this cohort, especially during the first year after diagnosis, in patients with pulmonary involvement and severe PR3 phenotype who received methylprednisolone boluses.