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 (HR a ) 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 HR a 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.