Brief communication: High incidence of venous thrombotic events among patients with Wegener granulomatosis: The Wegener's clinical occurrence of thrombosis (WeCLOT) study

Background: venous thrombotic events (VTEs) have been observed in Wegener granulomatosis, but the incidence rate is not known. Objective: To measure the incidence of VTEs in patients with Wegener granulomatosis. Design: Prospective, observational cohort study. Setting: A multicenter, randomized, double-blind, placebo-controlled treatment trial for Wegener granulomatosis. Patients: 180 patients with Wegener granulomatosis enrolled during periods of active disease. Measurements: venous thrombotic events (deep venous thromboses or pulmonary emboli) were documented and confirmed prospectively. Incidence rates were calculated on the basis of time to first VTE. Results: Thirteen patients had VTEs before enrollment. During 228 person-years of prospective follow-up, 16 VTEs occurred in 167 patients with no history of VTE. Median time from enrollment to VTE for patients with an event was 2.1 months. The incidence of VTE among patients with Wegener granulomatosis was 7.0 per 100 person-years (95% Cl, 4.0 to 11.4). Limitations: Although prospectively recorded, screening for VTEs did not occur. Conclusions: The incidence rate of VTEs in Wegener granulomatosis is high when compared with available rates in the general population, patients with lupus, and patients with rheumatoid arthritis. These results have important implications for clinical care of patients with Wegener granulomatosis.