Prevalence of postpartum venous thromboembolism risk factors in an Irish urban obstetric population

Abstract

Background Obstetric venous thromboembolism (VTE) is a leading cause of maternal morbidity and mortality. A clear understanding of the burden of VTE risk at a population level is a prerequisite to effective prevention; however, existing data are limited. Objectives Describe the prevalence and patterns of VTE risk factors among postpartum women and consider the implications for VTE prevention practices. Method We undertook a cross‐sectional study of prospectively collected data from sequential postpartum VTE risk assessments completed between January 2015 and December 2017 in the Rotunda Hospital, Dublin. Results We analyzed postpartum VTE risk factors in a large unselected Irish urban obstetric cohort of 21 019 consecutively sampled women. This represents more than 90% of all women giving birth in a single institution over a 3‐year period. The most common VTE risk factors related to maternal characteristics and delivery characteristics, including overweight and obesity (36%), age ≥35 (35%) and cesarean delivery (32%). More than three‐quarters of women had at least 1 VTE risk factor (78%) and more than 40% had multiple (2 or more) VTE risk factors. One‐fifth of women had no VTE risk factors before delivery, yet went on to develop VTE risk factors during delivery or in the postpartum period. Reflecting the differences in thromboprophylaxis thresholds internationally, the proportion of women who would have received a recommendation for postpartum thromboprophylaxis ranged from 7% to 37% under various clinical guidelines. Conclusion This study demonstrates the high prevalence of VTE risk factors among postpartum women. Postpartum VTE risk is highly individualized and complex.

Current and future burden of venous thrombosis: Not simply predictable

“…The majority, i.e, 82% of women, had at least one venous thrombosis risk factor (on top of pregancy) and over half of the women had two or more risk factors. Of all 16 218 women, 5380 (33.2%) were 35 years or older …”

VTE risk assessment in pregnancy

“…Although arguably the best‐quality data exist to address PA‐VTE risk reduction in women with a personal VTE history or inherited thrombophilia, these 2 categories of risk factor are rare (<1% in a recent large prospective study and intense debate .…”

“…In particular, the balance of thrombosis and bleeding risk is uncertain, and it is noteworthy that the 2018 ASH guideline panel highlighted important research needs, including a requirement for more data on the absolute VTE risk in women with combinations of known risk factors . Reflecting the lack of data, we recently performed an analysis of prospectively collected data from 21 019 consecutive comprehensive postpartum VTE risk assessments, applying the recommendations of representative international guidelines and calculating the proportion of women who would have received a recommendation for postpartum thromboprophylaxis under each guideline . This proportion ranged from 7% under American College of Obstetrics and Gynecologists guidelines to 37% under UK Royal College of Obstetricians and Gynaecologists guidelines (Table ).…”

“…Over three-quarters of women had at least 1 VTE risk factor (78%), and over 40% had multiple (2 or more) VTE risk factors. In 19% of women, all VTE risk developed during delivery or in the postpartum period (and were not present prior to the peripartum period; Figure 1), 36 highlighting the critical importance of performing VTE risk assessment after delivery.…”

“…Although arguably the best-quality data exist to address PA-VTE risk reduction in women with a personal VTE history or inherited thrombophilia, these 2 categories of risk factor are rare (<1% in a recent large prospective study. 36 ) The optimal strategy for PA-VTE prevention in women with more common VTE risk factors remains a critical knowledge gap, as evidenced (again) by widely varying international guideline recommendations 24,25,40,47,48 and intense debate. 49,50 In particular, the balance of thrombosis and bleeding risk is uncertain, and it is noteworthy that the 2018 ASH guideline panel highlighted important research needs, including a requirement for more data on the absolute VTE risk in women with combinations of known risk factors.…”