Clinical trial NCT02070237: Comparing Anti-XA Levels in Post-Cesarean Patients Undergoing Enoxaparin Thromboprophylaxis
Official title: Comparing Anti-XA Levels in Post-Cesarean Patients With BMI >35 Undergoing Enoxaparin Thromboprophylaxis With Weight Based Dosing Twice Daily Versus Fixed Dose 40 Milligrams Daily
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: Obesity
Obesity, Morbid
Pregnancy
Complications; Cesarean Section
Venous Thromboembolism
Postpartum Deep Phlebothrombosis
Pulmonary Embolism
Keywords: Obesity
Obesity, Morbid
Pregnancy
Cesarean
Venous thromboembolism
Deep venous thrombosis
Pulmonary embolism
Lead sponsor: MemorialCare Health System
Sponsor class: OTHER
First posted: 2014-02-25
Enrollment: 90
Sex: FEMALE
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: PREVENTION

Brief 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).

Detailed description: This is a multi-center, prospective, randomized controlled study to compare the proportion of patients that achieve the desired effect of LMWH (enoxaparin) thromboprophylaxis as measured by peak anti Xa level with weight based twice daily dosing versus standard fixed daily dosing. The investigators hypothesize that when enoxaparin is dosed by maternal weight and administered twice daily, the anti-factor Xa level would more frequently achieve prophylactic levels when compared to taking a fixed 40 mg of the drug daily.

Subjects will be women with a BMI \> 35 who have undergone a cesarean delivery and who will receive thromboprophylaxis with enoxaparin (Lovenox) at the judgment of their physician.

Women who are eligible and consent to participate in the study will be randomized in a 1:1 ratio to one of the following groups:

Group 1 will receive the weight based dosing (0.5mg/kg BID) enoxaparin (Lovenox®; Aventis Pharmaceuticals) regimen Group 2 will received the fixed dose (40mg daily) enoxaparin (Lovenox®; Aventis Pharmaceuticals) regimen.

Treatment will begin between 8 and 12 hours post operatively and this regimen will continue until discharge from the hospital, usually on the third or fourth day after surgery. A single peak anti Xa level will be drawn 3.5-4 hours after the third dose of medication. The results of the anti Xa level will only be for research purposes and will not guide clinical management.

The primary outcome for this study is to assess the peak anti-factor Xa level in the blood, and whether or not the subject achieved the desired prophylactic level when receiving fixed dose of enoxaparin compared with weight based dosing.

Eligibility criteria: Inclusion Criteria:

* Women with a body mass index \>35 who have undergone cesarean delivery in the last 12 hours who will receive thromboprophylaxis with enoxaparin
* Subjects who consent to the study.

Exclusion Criteria:

* Women with a previous history of deep venous thrombosis or pulmonary embolism
* Women who are currently receiving another form of low molecular weight heparin or unfractionated heparin.
* Women who are receiving other concomitant anticoagulant medications, such as warfarin, lepirudin, or argatroban.
* Subjects who are unable or unwilling to give informed consent.
* Women who, in the judgment of the investigators, would not be in the best interest of the patient to participate in the study.
* Allergy to enoxaparin.
* Women with renal impairment
* Women with contraindications to Lovenox treatment such as women with active bleeding or thrombocytopenia

Primary outcomes:
measure: Anti Xa Level
timeFrame: 3.5-4 hours after the third dose of Lovenox (enoxaparin)
Secondary outcomes:
measure: Supraprophylactic Range Anti Xa Level
timeFrame: 3.5-4 hours after the third dose of Lovenox (enoxaparin)
Other outcomes:
Locations:
city: Long Beach
country: United States
facility: Long Beach Memorial Care Center for Women at Miller Children's Hospital Long Beach and Long Beach Memorial Hospital
state: California
Study officials:
affiliation: Memorial Care Health System
name: Jennifer McNulty, MD
role: PRINCIPAL_INVESTIGATOR
affiliation: Memorial Health Care System; University of California Irvine
name: Megan L Stephenson, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Middleton P, Shepherd E, Gomersall JC. Venous thromboembolism prophylaxis for women at risk during pregnancy and the early postnatal period. Cochrane Database Syst Rev. 2021 Mar 29;3(3):CD001689. doi: 10.1002/14651858.CD001689.pub4.
citation: Stephenson ML, Serra AE, Neeper JM, Caballero DC, McNulty J. A randomized controlled trial of differing doses of postcesarean enoxaparin thromboprophylaxis in obese women. J Perinatol. 2016 Feb;36(2):95-9. doi: 10.1038/jp.2015.130. Epub 2015 Dec 10.