Long-term prospective study of recurrent venous thromboembolism in patients younger than 50 years.

Long-term incidence of recurrent venous thromboembolism (VTE) in patients younger than 50 years, not affected by a malignancy or chronic diseases, are poorly characterized. After the initial episode of VTE and cessation of oral anticoagulation, 98 patients, mean age 32.2+/-9.2 years were followed for a median of 117 months (range 6-165). Congenital risk factors for VTE were present in 36% of patients, acquired persistent (positive antiphospholipid antibodies during the whole follow-up) in 19%, and acquired transitory in 44%. Thirty episodes of recurrent VTE were documented. The cumulative incidence of VTE after 1 year of follow-up was 5.1%, 9.8% after 2 years, 14% after 4 years, and 34.2% after 8 years. In the univariate analysis, the relative risk of recurrent VTE was 2.66 [95% confidence interval (CI) 1.03-6.90] for congenital risk factors, 4.97 (95% CI 1.75-14.0) for persistent acquired (antiphospholipid antibodies), 2.64 (95% CI 1.23-5.66) for male gender and 2.27(1.00-5.15) for body mass index>30 kg/m2. In the multivariate analysis, male gender [hazard ratio (HR) 4.23, 95% CI 1.88-9.77) the presence of congenital factors (HR 3.28, 95% CI 1.25-8.63) and acquired persistent factors (HR 8.50, 95% CI 2.84-25.50) were independent risk factors for recurrent VTE. In patients under 50 years of age without malignancy or underlying chronic disease, hospitalized for an acute thromboembolic event, the presence of antiphospholipid antibodies, congenital defects of coagulation, male sex, and obesity were risk factors for recurrent VTE. These data raise the possibility that selected patients with VTE may require prolonged anticoagulation to prevent recurrent disease.