263: Maternal age and body mass index provide the best target population for venous thromboembolism prevention

Abstract

Venous thromboembolism (VTE) is a major cause of maternal morbidity and mortality. The purpose of this study was to determine the impact of different obstetric specific VTE treatment options. We performed a retrospective analysis of a large multicenter community based obstetric population to determine incidence of VTE and the impact (number needed to treat, or NNT) of applying different risk treatment options for pharmacologic VTE prophylaxis. All patients delivering or presenting for postpartum (PP) care from 1/2016 to 3/2018 that had an ICD10 code for VTE were identified. Cases were reviewed by a local perinatal safety nurse for accuracy and VTE risk factors. To determine the impact of applying specific clinical risk combinations the NNT was calculated based on the incidence of those clinical factors in the total obstetrical population. For modeling we assumed that treatment would prevent a VTE event with an efficacy of 100%, 75%, or 50% of those treated. The combination of risk factors with the lowest NNT was considered to have the best efficacy. During the 27-month review period there were 120,235 deliveries and 121 cases were coded for VTE. Of these, 95 had a VTE event in the index pregnancy (0.7 ±0.1/1,000 births). Treatment of all cesarean births (CS) performed the poorest (NNT=1,102 to 2204). Combinations of Age and body mass index (BMI) performed the best. AGE>35+BMI>35 and AGE>35+BMI>35+CS had the lowest NNTs, <1:200, <1:250, and <1:375 for 100%, 75%, and 50% treatment efficacy (Table). Targeting these two groups would reduce the number of PP VTE events by 12.3% (50% efficacy) to 24.5% (100% efficacy) (95% CI=6.5-37.6%). Other risk factors were too infrequent to provide reliable predictions in both antenatal and PP cases. In 37 cases the use of sequential compression devises (SCDs) could be determined. Lack of documented use or refusal to use SCDs was higher in the vaginal delivery group 13/18 (72%) v. CS (4/19 (22%), p<0.01. Most current recommendations for the prevention of VTE are not obstetric specific. We note that using delivery type, Age and BMI allows reasonable targeting of specific postpartum patients and should effectively reduce the number of PP VTEs. Increasing universal use of SCDs would likely augment the reduction in PP VTE.