59 Safety and efficacy of a risk-based obstetric heparin-based thromboprophylaxis regimen

Abstract

Contemporary guidelines recommend a risk-based approach to obstetric venous thromboembolism (VTE) prophylaxis (ppx), yet routine use of heparin-based ppx in obstetric patients is understudied. We examined the efficacy and safety of a risk-based protocol for heparin-based VTE ppx in obstetric patients. Retrospective cohort study of all deliveries at a single center from 2013-2018. Deliveries were categorized as pre- (2013-2015; no standard ppx) and post-protocol (2016-2018; risk-based protocol with heparin-based ppx). Patients anticoagulated for active VTE or high VTE risk were excluded. The primary efficacy outcome was diagnosis of any postpartum VTE; the primary safety outcome was any wound hematoma (other outcomes in Table 2). Outcomes were compared between pre- and post-protocol groups; adjusted odds ratios (95% CIs) were calculated using the pre-protocol group as reference. Numbers needed to treat (NNT) and harm (NNH) were assessed for VTE and wound hematoma, respectively. Of 24,229 total deliveries, 11,799 (49%) were pre-, and 12,430 (51%) were post-protocol. Baseline characteristics are presented in Table 1. Despite 15-times more anticoagulation use post-protocol (Table 2), there was no significant difference in VTE rate (0.1% vs 0.1%, NNT 61,713). Post-protocol, risk of wound hematomas (particularly superficial hematomas) significantly increased 2-fold (aOR 2.3 [1.5-3.6], NNH 333), as did unplanned procedures and blood transfusions despite more restrictive institutional transfusion practices post-protocol (Table 2). Interaction tests indicated no differences by mode of delivery (cesarean vs. vaginal) for VTE (p=0.24) or hematoma (p=0.31). Adoption of a risk-based anticoagulation protocol for obstetric VTE ppx was associated with increased wound hematomas, unplanned procedures, and blood transfusions without decreased VTEs. Given that, for every 60,000 obstetric patients under this protocol needed to prevent 1 VTE, there were an associated 180 wound hematomas, routine risk-based anticoagulation for VTE ppx in obstetric patients should be strongly reconsidered.View Large Image Figure ViewerDownload Hi-res image Download (PPT)