Postpartum Aspirin for Blood Clots

Recruiting at 2 trial locations

Overseen By Jill Baxter, BSc

Age: 18+

Sex: Female

Trial Phase: Phase 3

Sponsor: University of Calgary

Must not be taking: Anticoagulants, Aspirin

Disqualifiers: VTE history, Heart valve, APS, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Pivotal Trial (Near Approval) This treatment is in the last trial phase before FDA approval

Prior Safety Data This treatment has passed at least one previous human trial

Compensation: Varies

Number of Visits: 6

Duration: 6 weeks

8805 Participants Needed

Trial Summary

What is the purpose of this trial?

The goal of the PARTUM trial is to determine if taking low-dose aspirin daily for 6 weeks after delivery is similar (non-inferior) to usual care low-molecular-weight heparin injections to prevent venous thromboembolism (VTE: blood clots in the legs or lungs) for postpartum individuals with VTE risk factors.

Do I need to stop my current medications for the trial?

The trial information does not specify if you need to stop taking your current medications. It's best to discuss this with your doctor or the trial team.

What data supports the effectiveness of the drug aspirin for preventing blood clots after childbirth?

Research shows that aspirin (acetylsalicylic acid, ASA) is effective in preventing blood clots by inhibiting platelet function, which is important for clot formation. Additionally, low-dose ASA is well-established for preventing cardiovascular events, which involves similar mechanisms to preventing blood clots. ^{1 2 3 4 5}

Is aspirin safe for use in humans, especially during pregnancy?

Aspirin (acetylsalicylic acid) has been used safely for many years for its painkilling and anti-inflammatory effects. It is considered safe during pregnancy at low doses (not exceeding 100 mg daily) and is often used to prevent complications like pre-eclampsia and fetal growth restriction in high-risk patients. ^{1 2 4 6 7}

How does the drug aspirin differ from other treatments for postpartum blood clots?

Aspirin, when used with low-molecular-weight heparin, is unique for postpartum blood clots as it combines two agents that prevent blood clots by different mechanisms: aspirin inhibits platelet aggregation, while heparin prevents clot formation. This combination is particularly used in high-risk pregnancies, such as those with antiphospholipid syndrome, to improve outcomes without significantly increasing bleeding risks. ^{4 6 8 9 10}

Research Team

Leslie Skeith, MD

Principal Investigator

University of Calgary

Marc Rodger, MD

Principal Investigator

McGill University Health Centre/Research Institute of the McGill University Health Centre

Eligibility Criteria

The PARTUM trial is for individuals who have recently given birth and are at risk of developing blood clots. Participants must be in the postpartum period and meet certain criteria that put them at higher risk for venous thromboembolism.

Inclusion Criteria

I have had a clot in a vein near the surface of my body.

My BMI was 30 or higher before I got pregnant.

Preeclampsia

Exclusion Criteria

More than 48 hours since delivery at the time of randomization

I have received more than one dose of LMWH since giving birth.

Unable or declined consent

Timeline

Screening

Participants are screened for eligibility to participate in the trial

Up to 48 hours post-delivery

Treatment

Participants receive either low-dose aspirin daily or low-molecular-weight heparin as per site-specific regimen for 6 weeks

6 weeks

Follow-up

Participants are monitored for safety and effectiveness after treatment

90 days

Follow-up at 6 weeks and 90 days post-randomization

Treatment Details

Interventions

• Aspirin
• Low-molecular-weight heparin

Trial Overview This study tests if taking low-dose aspirin daily for six weeks after giving birth can prevent blood clots as effectively as the standard treatment with low-molecular-weight heparin injections.

Participant Groups

Group I: Aspirin Experimental Treatment 1 Intervention

Low-dose aspirin (75-100 mg) once daily for 6 weeks.

Group II: Low-molecular-weight heparin Active Control 1 Intervention

Site-specific low-molecular-weight heparin regimen as prescribed by the treating physician.

Aspirin is already approved in European Union, United States, Canada, China for the following indications:

Approved in European Union as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in United States as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in Canada as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention
• Preeclampsia prevention

Approved in China as Aspirin for:

• Pain relief
• Fever reduction
• Inflammation
• Cardiovascular disease prevention

Who Is Running the Clinical Trial?

University of Calgary

Lead Sponsor

Trials

827

Recruited

902,000+

Canadian Institutes of Health Research (CIHR)

Collaborator

Trials

1,417

Recruited

26,550,000+

Findings from Research

In a study involving healthy volunteers who took varying doses of acetylsalicylic acid (ASA) for one week, all doses significantly inhibited platelet function and increased bleeding times, indicating its effectiveness in thrombosis prophylaxis.

The research found that a daily dose of around 100 mg of ASA maximized the effects on platelet function and bleeding time, suggesting that higher doses do not provide additional benefits.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of different doses of some acetylsalicylic acid formulations on platelet function and bleeding times in healthy subjects. McLeod, LJ., Roberts, MS., Cossum, PA., et al.[2019]

Low-dose acetylsalicylic acid (ASA) significantly reduces the risk of pre-eclampsia and other pregnancy complications, with a notable reduction in rates of preterm birth and fetal growth restriction, based on a review of multiple studies.

ASA is generally safe for use during pregnancy, with rare side effects, primarily related to bleeding, making it a beneficial option for women at high risk of pregnancy-associated morbidity.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Role of Acetylsalicylic Acid in the Prevention of Pre-Eclampsia, Fetal Growth Restriction, and Preterm Birth. Stubert, J., Hinz, B., Berger, R.[2023]

In a study of 268 patients with acute cerebral ischemia treated with intravenous aspirin and low-dose heparin, the treatment was found to be safe, with only one case of symptomatic secondary intracerebral hemorrhage and a low incidence of gastrointestinal complications.

While the functional outcomes varied, with 28.3% of patients achieving a Rankin Scale score of 0 (no symptoms), the efficacy of this treatment needs further investigation in controlled trials to determine its effectiveness in acute stroke management.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Intravenously administered acetylsalicylic acid in combination with low-dose heparin in acute ischemic stroke: a safety analysis. Büttner, T., Hellwig, K., Müller, T., et al.[2013]

A study involving 46 healthy participants demonstrated that a novel 75 mg soft-gel capsule formulation of acetylsalicylic acid (ASA) is non-inferior to a marketed powder solution in reducing serum thromboxane B2 (TXB2), a marker for platelet aggregation.

Both formulations showed similar effectiveness in inhibiting TXB2, with no reported adverse events, suggesting that the soft-gel capsule could be a safe and effective alternative for preventing cardiovascular events.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Pharmacodynamics and pharmacokinetics of a novel, low-dose, soft-gel capsule of acetylsalicylic acid in comparison with an oral solution after single-dose administration to healthy volunteers: a phase I, two-way crossover study. Loprete, L., Leuratti, C., Scarsi, C., et al.[2021]

A quality improvement project in an academic OB/Gyn practice showed that implementing a standardized approach to aspirin (ASA) prescription significantly increased screening rates for preeclampsia risk from 47% to 99% among new obstetric patients.

Post-intervention, 79% of patients who screened positive received an ASA recommendation, demonstrating that the standardized process is effective and equitable, with no significant differences in recommendations based on race.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Leveraging quality improvement to promote health equity: standardization of prenatal aspirin recommendations. Gross, ME., Godecker, A., Hughes, A., et al.[2023]

All six aspirin preparations tested effectively inhibited platelet aggregation to a similar extent, indicating their efficacy in reducing blood clotting, which is important for preventing heart attacks and strokes.

Ecotrin and S.R.A. showed delayed effects and inhibited platelet aggregation without measurable levels of aspirin in the bloodstream, suggesting a unique mechanism of action possibly involving acetylation of cyclooxygenase in the liver.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Aspirin kinetics and platelet aggregation in man. Siebert, DJ., Bochner, F., Imhoff, DM., et al.[2019]

Aspirin is considered safe for use during pregnancy at daily doses not exceeding 100mg and has been shown to effectively prevent pre-eclampsia and fetal growth restriction in high-risk patients.

However, aspirin has not demonstrated benefits for preventing vascular placental disease in low-risk patients or for unexplained recurrent miscarriages.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Aspirin: Indications and use during pregnancy]. Belhomme, N., Doudnikoff, C., Polard, E., et al.[2018]

References

1. Denmark pubmed.ncbi.nlm.nih.gov

The effects of different doses of some acetylsalicylic acid formulations on platelet function and bleeding times in healthy subjects. [2019]

2. Germany pubmed.ncbi.nlm.nih.gov

The Role of Acetylsalicylic Acid in the Prevention of Pre-Eclampsia, Fetal Growth Restriction, and Preterm Birth. [2023]

3. United States pubmed.ncbi.nlm.nih.gov

Intravenously administered acetylsalicylic acid in combination with low-dose heparin in acute ischemic stroke: a safety analysis. [2013]

4. New Zealand pubmed.ncbi.nlm.nih.gov

Pharmacodynamics and pharmacokinetics of a novel, low-dose, soft-gel capsule of acetylsalicylic acid in comparison with an oral solution after single-dose administration to healthy volunteers: a phase I, two-way crossover study. [2021]

5. England pubmed.ncbi.nlm.nih.gov

Leveraging quality improvement to promote health equity: standardization of prenatal aspirin recommendations. [2023]

6. United States pubmed.ncbi.nlm.nih.gov

Aspirin kinetics and platelet aggregation in man. [2019]

7. France pubmed.ncbi.nlm.nih.gov

[Aspirin: Indications and use during pregnancy]. [2018]

8. United States pubmed.ncbi.nlm.nih.gov

Low-dose asprin use during pregnancy may be a potential risk for postpartum hemorrhage and increased blood loss: a systematic review and meta-analysis. [2023]

9. Switzerland pubmed.ncbi.nlm.nih.gov

Maternal hemorrhagic complications following prophylactic low-dose aspirin and dipyridamole therapy. [2018]

10. England pubmed.ncbi.nlm.nih.gov

Bleeding complications and antithrombotic treatment in 264 pregnancies in antiphospholipid syndrome. [2018]