Clinical trial NCT01357941: Need for Antepartum Thromboprophylaxis in Pregnant Women With One Prior Episode of Venous Thromboembolism (VTE)
Official title: Prospective Study Assessing the Need for Antepartum Thromboprophylaxis in Pregnant Women With One Prior Episode of Venous Thromboembolism
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Venous Thromboembolism
Deep Vein Thrombosis
Pulmonary Embolism
Keywords: venous thromboembolism
thromboembolism
deep vein thrombosis
pulmonary embolism
thromboprophylaxis
thrombosis
embolism and thrombosis
cardiovascular diseases
venous thrombosis
vascular diseases
anticoagulants
hematologic agents
cardiovascular agents
enoxaparin
dalteparin
tinzaparin
pregnancy complications
Lead sponsor: Hamilton Health Sciences Corporation
Sponsor class: OTHER
Collaborators: name: St. Joseph's Healthcare Hamilton
First posted: 2011-05-23
Enrollment: 203
Sex: FEMALE
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Observational model: COHORT
Time perspective: PROSPECTIVE
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Consecutive pregnant women with prior VTE diagnosed with accurate testing.

Brief summary: Pregnant women with a prior history of venous thromboembolism (VTE) are at increased risk of recurrent VTE. Current guidelines assessing the role of prophylaxis in pregnant women with prior VTE are based primarily on expert opinion and the optimal clinical management strategy remains unclear.

This multicentre, prospective cohort study aims to test the following hypotheses:

1. Antepartum prophylaxis with fixed-dose low molecular-weight heparin (LMWH) is safe, convenient and associated with an acceptably low risk of recurrent VTE in women with a single prior episode of VTE that was either unprovoked or associated with a minor transient risk factor. (Moderate risk cohort)
2. Withholding antepartum prophylaxis is safe (recurrence risk \<1%) in pregnant women with a single prior episode of VTE provoked by a major transient risk factor. (Low risk cohort)

All study patients will receive 6 weeks of postpartum prophylaxis.


Eligibility criteria: Inclusion Criteria:

* Confirmed pregnancy (positive serum or urine)
* At least 18 years of age
* History of one prior episode of VTE consisting of DVT (diagnosed by compression ultrasonography \[CUS\] or venography) and/or PE (diagnosed by ventilation-perfusion \[V/Q\] lung scintigraphy, computed tomographic pulmonary angiography \[CTPA\], or traditional pulmonary angiography)

Exclusion Criteria:

* Ongoing need for therapeutic anticoagulation for prevention or treatment of cardioembolic stroke
* Known high-risk thrombophilia (specifically antithrombin deficiency, protein S deficiency, protein C deficiency, homozygosity for the factor V Leiden or prothrombin G20210A mutations, antiphospholipid antibody or compound abnormalities)
* VTE within 3 months of the current pregnancy
* Clinical risk factor for initial episode of VTE, if present, not resolved (excluding pregnancy)
* Known contraindication to anticoagulation (including active, uncontrolled bleeding or major bleed within the previous 4 weeks)
* For patients with prior unprovoked VTE, contraindication to LMWH (including allergy, HIT, impaired renal function, osteoporosis)
* Geographic or social factors precluding follow-up
* Inability or unwillingness to provide informed consent

Primary outcomes:
measure: Symptomatic venous thromboembolism
timeFrame: antepartum period (expected average 7 months)
Secondary outcomes:
measure: Symptomatic recurrent venous thromboembolism
timeFrame: antepartum period (expected average 7 months) and first 3 months postpartum
measure: Symptomatic recurrent pulmonary embolism
timeFrame: antepartum period (expected average 7 months) and first 3 months postpartum
measure: Thrombocytopenia or heparin-induced thrombocytopenia (HIT)
timeFrame: antepartum period (expected average 7 months)
measure: Symptomatic osteoporosis
timeFrame: antepartum period (expected average 7 months) and first 3 months postpartum
measure: Other complications
timeFrame: antepartum (expected average 7 months) and within first 3 months postpartum
measure: Pregnancy complications and outcomes
timeFrame: antepartum period (expected average 7 months)
measure: Fetal anomalies
timeFrame: antepartum (expected average 7 months) and during first 3 months postpartum
measure: Major and minor bleeding
timeFrame: antepartum (expected average 7 months)
Other outcomes:
Locations:
city: Hamilton
country: Canada
facility: McMaster University Medical Centre
state: Ontario
city: Hamilton
country: Canada
facility: St. Joseph's Healthcare Hamilton
state: Ontario
Study officials:
affiliation: McMaster University Medical Centre
name: Shannon M Bates, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Brill-Edwards P, Ginsberg JS, Gent M, Hirsh J, Burrows R, Kearon C, Geerts W, Kovacs M, Weitz JI, Robinson KS, Whittom R, Couture G; Recurrence of Clot in This Pregnancy Study Group. Safety of withholding heparin in pregnant women with a history of venous thromboembolism. Recurrence of Clot in This Pregnancy Study Group. N Engl J Med. 2000 Nov 16;343(20):1439-44. doi: 10.1056/NEJM200011163432002.