High Incidence of Arterial and Venous Thrombosis in Antineutrophil Cytoplasmic Antibody-associated Vasculitis

Objective. To determine the incidence of arterial thrombotic events (ATE) and venous thromboembolism (VTE) in antineutrophil cytoplasmic antibody- associated vasculitis (AAV). Methods. This is a retrospective cohort study presenting the incidence of ATE (coronary events or ischemic stroke) and VTE [pulmonary embolism (PE) or deep venous thrombosis (DVT)] in patients diagnosed with AAV between 2005 and 2014. Results. There were 204 patients with AAV who were identified. Median followup for surviving patients was 5.8 (range 1-10) years, accounting for 1088 person-years (PY). The incidence of ATE was 2.67/100 PY (1.56 for coronary events and 1.10 for ischemic stroke) and for VTE was 1.47/100 PY (0.83 for DVT only and 0.64 for PE with/without DVT). On multivariate analysis, prior ischemic heart disease (IHD) and advancing age were the only independent predictors of ATE. Among patients without prior IHD or stroke, the incidence of ATE remained elevated at 2.32/100 PY (1.26 for coronary events and 1.06 for ischemic stroke). ATE, but not VTE, was an independent predictor of all-cause mortality. Event rates for both ATE and VTE were highest in the first year after diagnosis of AAV but remained above the population incidence during the 10-year followup period. In comparison to reported rates for the UK population, the event rates in our AAV patients were 15-times higher for coronary events, 11-times higher for incident stroke, and 20-times higher for VTE. Conclusion. Patients with AAV have a high incidence of arterial and venous thrombosis, particularly in the first year after diagnosis.