Abstract Number: OC 11.2
Meeting: ISTH 2020 Congress
Background: Guidelines for postpartum thromboprophylaxis are mostly expert-based and appear to differ widely. A decision analytic model suggests that a postpartum venous thromboembolism (VTE) risk ≥0.2% is an acceptable threshold to justify thromboprophylaxis, but the risk thresholds defined by current guidelines are unclear.
Aims: To compare the proportion of women at high risk (with recommended thromboprophylaxis) according to the RCOG, ACOG and ACCP guidelines, and to estimate their absolute risk of VTE.
Methods: Among all women who delivered at the Geneva University Hospitals in 01.2019, we collected relevant maternal, obstetrical and fetal characteristics through medical chart review. We determined for each woman the recommended strategy of thromboprophylaxis according to the 3 guidelines. We estimated individual absolute VTE risks using a validated risk prediction model (Sultan, BMJ 2016). Proportions of recommended thromboprophylaxis were compared using proportion tests and risks of VTE using Wilcoxon rank-sum tests. The local ethics committee approved the study.
Results: Among 344 consecutive women (mean age of 32.2y (SD 5.3); BMI of 24.0kg/m2 (SD 4.8)), elective and emergency C-sections (CS) occurred in 9.6% and 13.7%, respectively. The RCOG guideline categorized 40.1% (25.4% of vaginal deliveries (VD), 88.8% of CS) as high-risk. The ACOG and ACCP guidelines, which focus exclusively on CS, categorized 35.0% and 46.3% of CS as high-risk, respectively (RCOG vs. ACOG or ACCP P< 0.001 ; ACCP vs. ACOG P=0.15).
The median estimated risk of VTE were 0.05% (full cohort), 0.04% (VD) and 0.10% (CS). Absolute risks were greater in high-risk than low-risk, but the proportion of women with a risk ≥0.2% remained small (Table 1).
Conclusions: We found wide variations in prevalences of recommended thromboprophylaxis and their risk thresholds. The RCOG guideline recommends using thromboprophylaxis in 4/10 women, but given their 0.1% risk of VTE, their number needed to treat to prevent 1 VTE event may be very high.
|All (n=344)||VD (n=264)||CS (n=80)||CS (n=80)||CS (n=80)|
|TPX not recommended (median, P10-90)||0.04% (0.03-0.07)||0.04% (0.03-0.07)||0.09% (0.05-0.13)||0.09% (0.05-0.18)||0.08% (0.05-0.15)|
|TPX recommended (median, P10-90)||0.09% (0.04-0.21)||0.08% (0.03-0.17%)||0.11% (0.06-0.26%)||0.18% (0.08%-0.34%)||0.18% (0.09-0.34)|
|Risk ≥0.2% among TPX not recommended||0/206 (0%)||0/197 (0%)||0/9 (0%)||4/52 (7.7%)||0/43 (0%)|
|Risk ≥0.2% among TPX recommended||15/138 (10.9%)||3/67 (4.5%)||12/71 (16.9%)||8/28 (28.6%)||12/37 (32.4%)|
[Table 1. Estimated absolute risks of postpartum VTE and proportions of risks ≥0.2% according to the classifications of different guidelines.]
To cite this abstract in AMA style:Gassmann N, Viviano M, Fontana P, Righini M, Martinez De Tejada B, Blondon M. Comparison of Recommended Postpartum Thromboprophylaxis and of Absolute Risk Thresholds According to the RCOG, ACCP and ACOG Guidelines [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/comparison-of-recommended-postpartum-thromboprophylaxis-and-of-absolute-risk-thresholds-according-to-the-rcog-accp-and-acog-guidelines/. Accessed March 3, 2021.
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