Comparing Anti-XA Levels in Post-Cesarean Patients Undergoing Enoxaparin Thromboprophylaxis

Summary

Pregnant and recently postpartum women are at significantly higher risk of developing a blood clot in their arms or legs known as a deep venous thrombosis (DVT) and/or a blood clot in their lungs known as a pulmonary embolism (PE) compared to their non pregnant counterparts. It is estimated that this risk increases anywhere from 4 to 50 times higher in pregnant versus non-pregnant women and further increases almost 11 fold in the post partum period. This risk is almost doubled when the patient undergoes cesarean delivery. In 2011, the American College of Obstetricians and Gynecologists (ACOG) issued updated guidelines stating that for patients undergoing cesarean delivery with additional risk factors for clot or thromboembolism, protective (prophylactic) treatment with low molecular weight heparin (LMWH) a type of blood thinner should be considered. However, no specific guidelines about which risk factors should be considered, or what medication doses should be used were provided. The American College of Chest Physicians (ACCP) Evidence-Based Clinical Practice Guidelines published in 2012 delineated who should be given prophylaxis based on various risk factors, however acknowledged that the recommendations were based on weak quality evidence.

ACOG endorses either once or twice a day dosing for high risk patients after delivery and states that adjustments for obese women should be made on a case by case basis. However, there are limited studies on the dosing of LMWH in specific subpopulations including post operative patients, pregnant patients and obese patients. All of these studies have urged further investigation of the correct dosing for these high risk subjects due to changes associated with pregnancy and the level of medication in the blood that may put these patients at higher risk of venous thromboembolism. Many previous studies have shown that women in these high risk categories do not achieve protective levels of the medication measured with a laboratory test; anti Xa level. The investigators hypothesize that due to their dual risk, obese post-operative recently pregnant women may not be adequately protected with the daily fixed dose and might need more frequent dosing to protect them.

The objective of this study is to assess what proportion of women achieve the desired anti Xa level with the fixed daily dose versus twice daily weight based dosing (0.5 mg/kg).

Conditions

• Obesity
• Obesity, Morbid
• Pregnancy
• Complications; Cesarean Section
• Venous Thromboembolism
• Postpartum Deep Phlebothrombosis
• Pulmonary Embolism

Interventions

DRUG

Enoxaparin

Enoxaparin will be given in either once daily or twice daily doses. One arm will receive 40 mg enoxaparin subcutaneous injection daily. The other arm will receive 0.5 mg/kg dosed subcutaneously twice daily. This medication will be started 8-12 hours after cesarean section and will be continued while the patient is admitted. It will be stopped at the time of discharge.

Sponsors & Collaborators

• MemorialCare Health System

  lead OTHER

Principal Investigators

• Jennifer McNulty, MD · Memorial Care Health System

• Megan L Stephenson, MD · Memorial Health Care System; University of California Irvine

Study Design

Allocation

RANDOMIZED

Purpose

PREVENTION

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

FEMALE

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2013-08-31

Primary Completion

2014-03-31

Completion

2014-03-31

Countries

• United States

Study Locations