Risk factors for recurrent venous thromboembolism in young and middle-aged women.

ABSTRACT

BACKGROUND: It is a matter of debate whether women with an episode of VTE associated with estrogen have a lower risk of recurrence than women with an unprovoked VTE. OBJECTIVES: To identify risk factors for recurrent VTE in women and to assess the risk of recurrent VTE associated with combined oral contraceptives (CHC) or menopausal hormone treatment (HT), compared to surgery-related and unprovoked VTE. PATIENTS/METHODS: A cohort of 974 women aged 18-64 years with a first episode of VTE were followed-up for a median time of 5.2 years. All women were previously included as cases in the Swedish nation-wide case-control study "Thrombo Embolism Hormone Study" (TEHS). Hazard ratios for recurrence were calculated using univariable and multivariable Cox proportional hazards model. RESULTS: A total of 102 patients (10%) suffered from recurrent VTE. The annual rate of recurrence was 1.0% in patients with surgery/cast, 2.0% in patients with CHC/HT and 3.2% in patients with unprovoked first VTE. Adjusted hazards ratio (HRa) for recurrence was 0.35 (95% CI 0.20-0.61) in women with VT provoked by surgery/cast while women with estrogen-associated VTE had a HRa of 0.70 (95% CI 0.43-1.20) compared to women with unprovoked VTE. CONCLUSION: Women 18-64 years are at low risk of recurrent VTE. Women with hormone associated VTE had a lower risk of recurrence than women with unprovoked VTE, but not as low as surgery/cast provoked VTE.