PROSPER: PostpaRtum PrOphylaxiS for PE Randomized Control Trial Pilot

• Feasibility of recruitment and trial operations. [ Time Frame: 6 months ] [ Designated as safety issue: No ]

  The number of subjects that are recruited per site per month during a 6 month active recruitment phase at each site.

  Secondary measures of feasibility will include:

  • Consent rate for eligible women and reasons for non-consent
  • Rates of compliance with blinded study drug administration
  • Rates of compliance with primary outcome assessment
  • Rates of withdrawal or loss to follow-up within 90 days
  • Length of time required to obtain ethics approval and institutional approvals for conducting the study at Canadian and US sites.
  
  

• Venous Thromboembolism in the early postpartum period. [ Time Frame: From randomization to Day 21 ] [ Designated as safety issue: No ]
  This includes symptomatic Deep Vein Thrombosis (DVT) or pulmonary embolism (PE) in the interval between randomization and the last dose of study drug (3 weeks+/- 3 days) OR asymptomatic proximal DVT detected by compression ultrasound of both legs done within 24hrs of the last dose of study drug (3 weeks (+/- 3 days) postpartum). Compressed and non-compressed images will be obtained from the calf trifurcation to the inguinal ligament. All suspected outcomes will be adjudicated by a blinded expert adjudication committee.
  
  
• Late symptomatic Venous Thromboembolism [ Time Frame: From Day 21 to Day 90 ] [ Designated as safety issue: No ]
  This includes symptomatic Deep Vein Thrombosis or Pulmonary Embolism. Suspected outcomes will be adjudicated by a blinded adjudication committee.
  
  
• Death From Venous Thromboembolism [ Time Frame: From Randomization to Day 90 ] [ Designated as safety issue: No ]

  If a subject dies between randomization and late postpartum follow up (Day 90 +/- 7 days) the death will be adjudicated as certain, highly probable, probable, or unlikely due to Pulmonary Embolism (PE) using the following criteria.

  Certain: hypotension, hypoxia, cardiac arrest with no other explanation other than PE and autopsy or radiographic confirmation Highly probable: criteria for certain but another disease could have caused the death Probable: other cause suspected based on clinical evidence but 100% certainty not available Unlikely: all other cases.

  
  
• Major Bleeding or clinically relevant non-major bleeding [ Time Frame: From Randomization to Day 90 ] [ Designated as safety issue: Yes ]

  Major bleeding meets at least one of the following: Fatal bleeding; Symptomatic bleeding in a critical area or organ (intracranial, intraspinal, retroperitoneal, etc.); Bleeding causing a fall in hemoglobin level of 20 g L−1 (1.24 mmol L−1) or more, or leading to transfusion of two or more units of whole blood or red cells .

  Clinically Relevant Non-major Bleeding does not meet the criteria for major bleeding but meets at least one of the following: Hospitalization; Medical intervention; Unscheduled contact with a physician; Discomfort (pain, or impairment of activities of daily life).

  
  
• Heparin Induced Thrombocytopenia [ Time Frame: From Randomization to Day 90 ] [ Designated as safety issue: Yes ]
  All subjects who develop thrombocytopenia (platelets less than 80 x 109/L and/or with >50% decrease from baseline) will be investigated for Heparin Induced Thrombocytopenia (HIT) by having ELISA and serotonin release assays to confirm or refute a diagnosis of HIT. HIT will be diagnosed with a positive PF4 HIT ELISA assay.
  
  

The PROPSER pilot is a randomized, double-blind, placebo-controlled pilot study comparing prophylactic low molecular weight heparin (LMWH) to saline placebo. The PROSPER pilot study will assess the feasibility of conducting a full trial as measured by the number of subjects recruited per center per month. In addition, clinical data will be collected to determine an estimate of the primary outcome event rate (symptomatic VTE or asymptomatic proximal deep vein thrombosis (DVT) and major bleeding event rate for the full trial in LMWH and placebo groups. If our pilot results indicate that no substantial changes are needed to the study design, we will include the pilot data in the primary and secondary outcome analyses for the full trial (i.e. a "Vanguard trial" or internal pilot trial).

Eligible consenting women at risk of postpartum thrombosis will be randomized within 36 hours after delivery of the placenta and will be equally and blindly allocated to 2 trial arms, either the treatment group: prophylactic-dose LMWH, subcutaneously once daily, or the control group (placebo): saline subcutaneously once daily. All participating women will continue to administer subcutaneous study drug daily for 3 weeks (+/- 3 days) for a total of 21 (+/-3) study drug injections.

At 3 weeks (+/- 3 days), women will have a study visit to assess for study outcomes, including bilateral leg ultrasound screening for VTE. A final telephone follow-up will occur at 90 days for outcome assessment of subsequent VTE, bleeding or other adverse events.