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Scoring tool offers personalized prophylaxis for pregnant women at risk for VTE

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May 2, 2017

A risk stratification tool for the risk assessment and management of venous thromboembolism during pregnancy may offer an effective and personalized approach to prophylaxis, according to prospective study results.

Patients with thrombophilia or who have a history of VTE are at risk for thrombosis during pregnancy; however, no validated tool exists to help clinicians stratify risk in pregnant women and introduce prophylactic anticoagulation at the appropriate time.

“Recommendations mostly based on case–control studies and expert opinions do not accurately reflect the physician’s need, and the management of VTE risk in pregnancy remains a challenge,” Yesim Dargaud, MD, PhD, professor of hematology at the Lyon Hemophilia Center and Clinical Haemostasis Unit of University of Lyon in France, and colleagues wrote. “The use of a risk stratification tool that takes all individual risk factors for VTE into consideration and that aids in making decisions regarding prophylaxis regimens may help.”

The Lyon VTE score — designed to rate patients at an increased risk for VTE and recommend individualized, tailored management — has shown favorable outcomes in retrospective studies.

Researchers evaluated the efficacy and tolerability of the three-pronged Lyon VTE score — which incorporates history of VTE, known thrombophilia markers and contemporary risk factors dependent on current pregnancy — in 542 consecutive pregnancies among 445 patients (mean age, 33 years) at high risk for VTE managed over 10 years.

In total, 279 patients (62.7%) had a personal history of VTE, 299 patients (67.2%) had a thrombophilia marker, and 131 patients (29.4%) with thrombophilia had a personal history of VTE.

Researchers used the risk scoring system to assign patients to one of three prophylaxis strategies during pregnancy:

  • Moderate risk (score < 3): The patient does not receive low–molecular-weight heparin (LMWH) during the antepartum period;
  • High risk (score 3-5): A prophylactic dose of LMWH is introduced in the third trimester; and
  • Very high risk (score 6): The prophylactic dose of LMWH is prescribed early during pregnancy.

Overall, 158 (35.5%) patients had a computed score below 3, of whom 22.7% had a personal history of VTE and 79.1% had thrombophilia.

Another 153 (34.4%) patients had a score of 3 to 5, of whom 92% had a history of VTE and 66.7% had thrombophilia.

The remaining 134 (30.1%) patients had a score of 6 or greater, all of whom had a history of VTE and 41% of whom had thrombophilia.

In total, 139 patients at moderate risk received LMWH prophylaxis in the postpartum period only. Nineteen patients originally assigned the moderate-risk group underwent bed rest to prevent preterm delivery and were moved to the high-risk group, so 172 high-risk patients received prophylaxis in the third trimester and postpartum. All 134 very high–risk patients were treated during their entire pregnancy. All patients received LMWH for at least 6 weeks in the postpartum period.

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During 10 years of study, six episodes of deep vein thrombosis occurred. These included two antepartum-related VTE events (0.37%) — one in the moderate-risk group and one in the very high–risk group — and four postpartum-related VTE events, three in the high-risk group and one in the very high–risk group.

No cases of pulmonary embolism occurred.

Two patients (0.37%) had bleeding, but no serious bleeding required transfusions or surgery.

“Our data emphasize the need for individualization of antithrombotic prophylaxis during the puerperium to help prevent the majority of thromboses that can occur during this period,” Dargaud and colleagues wrote.

The tool allowed 158 women with a low score to be spared 9 months of LMWH prophylaxis and 153 women with a score of 3 to 5 to be spared 6 months of LMWH prophylaxis, with only 0.37% experiencing antepartum-related VTEs and 0.37% with bleeds, the researchers added.

“The use of such tools offers the prospect of personalized medicine, which is more effective and probably more cost-efficient than ‘inclusive, equal treatment for all,’” the researchers wrote. “This last point, as well as the value of individualization of care in the postpartum period, needs to be confirmed in future studies.” – by Kristie L. Kahl

Disclosure: The researchers report no relevant financial disclosures.