High risk of long-term recurrence after a first episode of venous thromboembolism during pregnancy or postpartum: the REcurrence after a PrEgnAncy related Thrombosis (REPEAT) Study.

Introduction: Long term-recurrence risk following a pregnancy associated venous thromboembolism (VTE) is sparsely assessed.

Objective: To determine the rate of recurrence after a pregnancy associated VTE, and identify associated risk factors.

Method: Five hundred and eighty-seven women with a history of first VTE occurring during pregnancy or until 3 months after delivery were referred to La Timone Hospital, Marseille, France. Women were consecutively included between 2000 and 2015. VTE characteristics and biological parameters were collected at inclusion. During the 2016-2019 period, patients were recontacted to gather information on post-inclusion VTE. A weighted Cox model, adapted to the study's ambispective design, was used to analyse pre- and post-inclusion VTE recurrences.

Results: After quality controls, 583 women were analyzed. Incidence of recurrent VTE was 2.4% person-years. Cumulative risk of VTE recurrence was 38% (n=221), with a median follow-up of 31 years (95%CI [27-35]); 6%, 13%, 17%, 30% at 2, 5, 10 and 30 years respectively. Pulmonary embolism (PE) at first event was associated with a 2-fold increased risk of PE at recurrence compared with isolated deep venous thrombosis (DVT, Hazard Ratio (HR)=2.63, 95%CI [1.44-4.82]). Risk factors significantly associated with recurrence were: interrupted pregnancies (HR=1.85, 95%CI [1.18-2.90]; lower limb DVT (HR=2.95, 95%CI [1.16-7.49] and AB blood group (HR=1.71, 95%CI [1.06-2.77]).

Conclusion: Although the recurrence risk is low within the first 10 years after a pregnancy associated VTE, 1/3 patients experienced a new event over a 30-year period. Interrupted pregnancies, lower limb DVT, and AB blood group were associated with higher risk of recurrence.