Risk of recurrence after a first venous thromboembolic event in young women.

BACKGROUND AND OBJECTIVES Few data are available on the long-term risk of recurrence of venous thromboembolism (VTE) and on the impact of established thrombosis risk factors in young women. We aimed to study the recurrence rate and the predictive value of laboratory and clinical thrombosis risk factors in young women. DESIGN AND METHODS Three-hundred and sixty-one women with a first objectively confirmed VTE under 45 years of age (median age 29.6 years, interquartile range 21.9-36.9) known to our outpatient department were included in this retrospective analysis. These women were re-examined with regard to recurrence of thrombosis and laboratory thrombosis risk factors. RESULTS Within a median observation period of 11.3 years, recurrent VTE occurred in 141 patients (39.2%). The cumulative probability of recurrence was 10.9% after 2 years, 29% after 10 years and 56% after 20 years. There were no significant associations between recurrence of VTE and laboratory risk factors such as natural inhibitor deficiency, factor V Leiden, the G20210A prothrombin variation, elevated factor VIII or hyperhomocysteinemia. Even women with more than one risk factor were not found to have a higher risk of recurrent VTE. Among the clinical characteristics only an increased body mass index (p=0.03) was associated with a higher probability of recurrence. INTERPRETATION AND CONCLUSIONS The risk of recurrent VTE in young women is higher than previously expected and remains constant over at least 20 years. Neither clinical features nor laboratory parameters help predict this risk. Thus, also in young women VTE should be regarded as a chronic disease.