794 Venous thromboembolism and adverse outcomes in highest-VTE risk gravidas compared to those at lower risk

Abstract

At our institution, we found that a risk-based protocol for inpatient heparin-based venous thromboembolism (VTE) prophylaxis (ppx) in obstetric patients with low- and medium-VTE risk resulted in 180 hematomas for every 1 VTE prevented. Herein, we compare rates of VTE and bleeding outcomes in women at highest risk for VTE (i.e. high-risk thrombophilia, active VTE who require anticoagulation ppx or therapy (tx) throughout pregnancy) compared to lower-risk gravidas. Retrospective cohort study of all deliveries >20 weeks at a single center (2013-2018). Women were categorized as high-risk (HR; received outpatient heparin-based ppx/tx, see Table 1 footnote for all indications) or lower-risk (LR; no outpatient anticoagulation).The primary efficacy outcome was any newly diagnosed postpartum VTE; the primary safety outcome was wound/perineal hematoma (all outcomes in Table 2). Outcomes were compared between HR and LR cohorts; adjusted odds ratios (95% CIs) were calculated with the LR group as reference. Of 24,303 total deliveries, 398 (2%) were HR, and 23,905 (98%) were LR. Of LR women, 8.6% received anticoagulation ppx in accordance with our risk-based inpatient VTE ppx protocol. HR and LR women were significantly different at baseline (Table 1). Despite outpatient antepartum anticoagulation, HR women had a 10-fold increased risk of VTE (aOR 10.6 [4.4-25.1] compared to LR women. HR women also had significantly more wound/perineal hematomas (aOR 2.5 [1.1-5.8]), overall wound/postoperative complications, blood transfusions, ICU admissions, maternal deaths and longer maternal lengths of stay (Table 2). Women at highest risk for obstetric VTE had significantly more VTEs and postpartum wound/bleeding complications when compared to LR women. Given the 10-fold increased risk of VTE in these high-risk women, even with outpatient anticoagulation, with only a moderate increase in adverse bleeding outcomes, this favorable risk/benefit profile supports current anticoagulation recommendations in HR women, while it questions routine obstetric VTE ppx in LR women (NNT 60,000; NNH 333).View Large Image Figure ViewerDownload Hi-res image Download (PPT)