Incidence and predictors of severe infections in ANCA-associated vasculitis in a population-based cohort – preliminary results

Background: Infectious complications in ANCA associated vasculitis (AAV) are a major cause of morbidity and mortality. The aim of this study was to determine the incidence rates, predictors and outcome of severe infections in AAV. Methods: We conducted a population-based cohort study in Southern Sweden with 326 incident cases of AAV diagnosed between 1997 and 2016. Diagnosis of vasculitis was confirmed by case record review and patients were classified according to the European Medicines Agency algorithm. Demographics, clinical, andlaboratory data was collected from time of diagnosis and follow-up. All events of severe infection (required hospitalization and treated with intravenous antimicrobials) were identified. Vasculitis disease activity was evaluated using the Birmingham Vasculitis Activity Score (BVAS) and the extent of organ damage was assessed using the vasculitis damage index (VDI). Patients were followed from time of AAV-diagnosis to death or end of study, December 2017Results: Data on 262 patients (122 women) was collated and are presented in this report. Total time of follow-up was 1368 person-year. In total 104 (39.7%) patients experienced at least one severe infection during the follow-up, 33 (12.5%) suffered 2 infections and 14 (5%) suffered 3 severe infections or more. The incidence rate of severe infection was higher during the first year after diagnosis compared to that during the whole follow-up time (24.3/100 year vs. 7.6/100, p<0.001). Patients with severe infection were older at diagnosis, had higher serum creatinine, higher BVAS at diagnosis and higher VDI after 12 months (Table 1). They were also more likely to be MPO-ANCA positive. Age and BVAS at diagnosis were the only factors that independently predicted severe infection. Severe infection was associated with worse prognosis in terms of renal and patient’s survival. Conclusion: In this cohort the incidence rate of severe infection is comparable to earlier published data in AAV. The rate of severe infection is higher early in the disease course. Severe infection is still a major clinical problem and is associated with high age, increased disease activity at diagnosis, renal disease and MPO-ANCA positivity. Severe infection is associated with a worse prognosis.