new study published in the journal Obstetrics & Gynecology indicates that
weight-based enoxaparin dosing is significantly more effective than body mass
index (BMI) based dosing for venous thromboembolism (VTE) prophylaxis among
morbidly obese women after a cesarean delivery.
from the University of California, San Diego, carried out a prospective
sequential cohort study involving women with BMI of 40 or greater who went
through cesarean delivery.
many as 42 of these morbidly obese women were assigned to weight-based enoxaparin
, and a total number of 43 women
received BMI-stratified dosing.
the weight-based dosing regimen, the women received 0.5 mg/kg of enoxaparin
every 12 hours. As per the BMI-based regimen, participants with BMIs of 40 -
59.9 were administered 40 mg enoxaparin every 12 hours and participants with
BMIs of 60 or greater received 60 mg enoxaparin every 12 hours.
show that the weight-based group received significantly higher concentrations
of anti-Xa compared with the BMI-stratified group (0.29 international units per
mL vs. 0.17 international units per mL).
per the results, while about 36 participants (86%) of the weight-based dosing
group received anti-Xa concentrations within the prophylactic range or
preventive range for VTE, only 11 participants (26%) of the BMI-stratified
dosing group reached the specified range.
no participants met the threshold for venous thromboembolism prophylaxis or
anti-Xa concentration of 0.6 IU/mL or greater.
author, Rachael T. Overcash, MD, MPH, and her research team from the University
concluded that weight-based dosing of enoxaparin for VTE prophylaxis is
significantly more effective than BMI-stratified dosing in achieving adequate
anti-Xa concentrations in morbidly obese women after cesarean delivery.
researchers acknowledge that this study was limited by a relatively small
sample size, lack of long-term clinical outcome data, and the use of only a
single anti-Xa level. However, they were able to predict the peak anti-Xa
levels fairly well. They attempted to quantify anti-Xa levels after both the
first and second dose, due to an average length of stay of only three days, but
that was often not possible. This study concentrated mainly on a weight-based
dosing algorithm leading to predictable peak anti-Xa levels in obese patients
and not on clinical outcomes. Although this study gives a better idea on how to
optimally prescribe VTE prophylaxis in morbidly obese patients, further studies
are necessary as an optimal approach still remains unproven.
Background and Importance of the Research
is the development of blood clots in the vein.
When a clot forms in a deep vein, it is called a deep vein thrombosis or DVT.
If the clot breaks loose and travels to the lungs, it could lead to a condition
known as pulmonary embolism or PE, which could be a life-threatening event.
Together, DVT and PE are known as VTE, - a dangerous medical condition.
remains a major cause of maternal morbidity and mortality during pregnancy.
According to researchers, cesarean delivery doubles the risk of venous
thromboembolism with half occurring postpartum - the period starting from the
birth of a child and extending for about six weeks.
is a significant risk factor for the formation of VTE. Morbidly obese women or
women who are 100 pounds over their ideal
have a four-fold greater rate of VTE postpartum than
normal women. Also, studies have shown that obese women are more likely to
deliver by cesarean method and suffer postpartum complications than non-obese
current guidelines advise that obese women get at a minimum pneumatic
compression devices for VTE prevention after cesarean delivery. The devices
consist of an inflatable garment for the arm, leg, trunk, or chest and an
electrical pneumatic pump.
researchers from the University state that there is no consensus with respect
to the use, dosage, timing, or duration of anticoagulation medication in this
is the recommended anticoagulant for VTE prevention in pregnancy, and the
recommended thromboprophylactic dose of enoxaparin is 40 mg daily. The anti-Xa
test is an assay method that estimates the direct inhibition of factor Xa by
enoxaparin. For prophylactic anticoagulation, anti-Xa concentrations between
0.2 and 0.6 international units per milliliter (IU/mL) are considered enough.
or morbid obesity changes the bioavailability and distribution of enoxaparin.
There are limited researches conducted so far on the correct dosing for
enoxaparin in obese women after cesarean delivery. The current study gives a
correct enoxaparin dosing strategy to treat VTE in morbidly obese women after
Obstetrics & Gynecology: June 2015 - Volume 125 - Issue 6 - p 1371-1376