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Vergelijking van het bloedingsrisico tussen rivaroxaban en apixaban bij patiënten met boezemfibrilleren (COBRRA-AF)

30 september 2026 bijgewerkt door: Ottawa Hospital Research Institute

Atrial Fibrillation (AF) affects 200,000 Canadians and increases risk of stroke, morbidity and mortality. Having a stroke can affect a patient's ability to speak, eat, walk, work, care for themselves, and interact with others. Not only can it ruin one's life, but it can also be fatal. A stroke occurs when blood flow to the brain is blocked by a clot, depriving brain cells of oxygen. In people with atrial fibrillation, blood flow is sluggish in the top chambers of the heart, and blood clots can form there. When a piece of a clot breaks off, it can travel to the brain and cause a stroke. That's where blood thinners come in. Blood thinners, or anticoagulants, decrease the chances of blood clots forming in the heart, reducing the risk of stroke. Studies show that blood thinners are highly effective at reducing the risk of stroke by up to 95%.

The conventional blood thinner is warfarin, taken by mouth. Warfarin requires regular blood tests to make sure a patient getting the correct dose. The patient also may have to avoid certain foods since the medication can interact with them. Newer blood thinners, known as direct-oral anticoagulants (DOACs) are available, which do not require regular blood tests and do not interact with foods. Two of the new blood thinners are called rivaroxaban and apixaban. Like warfarin, they can be taken by mouth, and studies have shown them to be as effective as warfarin.

Both rivaroxaban and apixaban have been approved for stroke prevention in AF by Health Canada. However, there have been no direct head-to-head comparisons of these two anticoagulants, meaning comparative safety data is not available. Increasing use of DOACs for stroke prevention in AF and patient values around bleeding highlight the need for a comparison trial to ensure patients receive the anticoagulant with the greatest balance of benefit to potential harm.

The trial is to assess bleeding rates and superiority of using apixaban versus rivaroxaban in patients with non-valvular atrial fibrillation.

Studie Overzicht

Toestand

Werving

Conditie

Interventie / Behandeling

Gedetailleerde beschrijving

Atrial Fibrillation (AF) affects 200,000 Canadians and increases risk of stroke, morbidity and mortality. Oral anticoagulants such as Vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) are highly effective at reducing the risk of stroke by up to 95%. Randomized controlled trials (RCTs) have compared apixaban and rivaroxaban (both DOACs) to VKAs for stroke prevention in AF, and are approved for this use by Health Canada. However, there have been no direct head-to-head comparisons of these two anticoagulants, meaning comparative safety data is not available. Increasing use of DOACs for stroke prevention in AF, patient values around bleeding, and litigation highlight the need for a comparison trial to ensure patients receive the anticoagulant with the greatest balance of benefit to potential harm.

The objective of this RCT is to compare the safety of the first 12 months of apixaban twice daily to rivaroxaban once daily in patients with non-valvular AF (NVAF). Patients will be monitored for the primary outcome of clinically relevant bleeding (CRB; a composite of major bleeding (MB) and clinically relevant non-major bleeding (CRNMB) events during follow-up. This trial will directly inform clinical practice and the choice of first-line therapy.

Studietype

Ingrijpend

Inschrijving (Geschat)

3018

Fase

  • Fase 4

Contacten en locaties

In dit gedeelte vindt u de contactgegevens van degenen die het onderzoek uitvoeren en informatie over waar dit onderzoek wordt uitgevoerd.

Studiecontact

Studie Contact Back-up

Studie Locaties

  • Canada
    • British Columbia
      • Victoria, British Columbia, Canada, V8Z 0B9
        • Ingetrokken
        • Victoria Cardiac Arrhythmia Trials
    • Nova Scotia
      • Halifax, Nova Scotia, Canada
        • Werving
        • QEII Health Science Centre
        • Hoofdonderzoeker:
          • Ratika Parkash, MD
        • Contact:
    • Ontario
      • Kingston, Ontario, Canada
      • Ottawa, Ontario, Canada, K1H 8L6
        • Werving
        • The Ottawa Hospital - General Campus
        • Hoofdonderzoeker:
          • Lana Castellucci, MD
        • Contact:
        • Contact:
      • Ottawa, Ontario, Canada
        • Werving
        • University Ottawa Heart Institute
        • Contact:
        • Contact:
        • Hoofdonderzoeker:
          • Daniel Ramirez, MD
    • Quebec

Deelname Criteria

Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.

Geschiktheidscriteria

Leeftijden die in aanmerking komen voor studie

18 jaar en ouder (Volwassen, Oudere volwassene)

Accepteert gezonde vrijwilligers

Nee

Geslachten die in aanmerking komen voor studie

Allemaal

Beschrijving

Inclusion Criteria:

  • Age ≥ 18 years old
  • Confirmed new diagnosis of AF on ECG with an indication to start anticoagulation according to Canadian Cardiovascular Society guidelines

Exclusion Criteria:

  • Creatinine clearance =<15 ml/min calculated using the Cockcroft-Gault formula

  • Any contraindication for anticoagulation with apixaban or rivaroxaban as determined by the treating physician such as, but not limited to:

    • active bleeding
    • history of mechanical valve
    • other indication for anticoagulation (e.g. mechanical valves, venous thrombosis)
    • dual antiplatelet agent use
    • known liver disease with coagulopathy
    • use of contraindicated medications (strong inducers/inhibitors of CYP 3A4/5, P-glycoprotein)
    • pregnancy or breastfeeding

Studie plan

Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.

Hoe is de studie opgezet?

Ontwerpdetails

  • Primair doel: Behandeling
  • Toewijzing: Gerandomiseerd
  • Interventioneel model: Parallelle opdracht
  • Masker: Enkel

Wapens en interventies

Deelnemersgroep / Arm
Interventie / Behandeling
Actieve vergelijker: Apixaban group

5 mg PO, twice daily for 12 months of treatment. A dose reduction* to 2.5 mg twice daily will apply if patients meet 2 of 3 following criteria: age > 80 years; weight < 60 kg; creatinine >133 micromol/L.

*Patients with AF who are receiving DOAC should have their renal function assessed at baseline and at least annually
Geneesmiddel: Apixaban

Refer to Apixaban group

Andere namen:
  • Eliquis
Actieve vergelijker: Rivaroxaban Group

20 mg PO, once daily for 12 months of treatment. A dose reduction* to 15 mg daily will apply to patients with creatinine clearance <50 ml/min.

*Patients with AF who are receiving DOAC should have their renal function assessed at baseline and at least annually
Geneesmiddel: Rivaroxaban

Refer to Rivaroxaban group

Andere namen:
  • Xarelto

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
The rate of adjudicated clinically relevant bleeding (CRB) events
Tijdsspanne: For the duration of the study: 12 months

CRB events are defined as the composite of major bleeding (MB) events and clinically relevant non-major bleeding (CRNMB) events
For the duration of the study: 12 months

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Adjudicated Major Bleeding events
Tijdsspanne: For the duration of the study: 12 months

Major Bleeding includes clinically overt bleeding and is associated with:

  • Fatal bleeding, and/or
  • Symptomatic bleeding in a critical area or organ, such as intracranial, intraspinal, intraocular, retroperitoneal, intra-articular or pericardial, or intramuscular with compartment syndrome, and/or
  • A fall in hemoglobin of ≥20 g/L, or
  • Leading to transfusion of ≥2 units of whole blood or red cells.
For the duration of the study: 12 months
Adjudicated Clinically Relevant Non-Major Bleeding events
Tijdsspanne: For the duration of the study: 12 months

Clinically relevant non-major bleeding will be defined as:

• Any sign or symptom of hemorrhage (e.g., more bleeding than would be expected for a clinical circumstance, including bleeding found by imaging alone) that does not fit the criteria for the ISTH definition of major bleeding but does meet at least one of the following criteria:

  • Requiring medical intervention by a healthcare professional
  • Leading to hospitalization or increased level of care
  • Prompting a face to face (i.e., not just a telephone or electronic communication) evaluation
For the duration of the study: 12 months
Adjudicated stroke/TIA events
Tijdsspanne: For the duration of the study: 12 months

Stroke is defined as non-traumatic focal neurologic deficit lasting ≥ 24 hours and confirmed on cerebral imaging (computed tomography or magnetic resonance imaging).

Transient ischemic attack (TIA) is defined as a temporary loss of blood flow to a part of the brain with focal neurologic deficit lasting < 24 hours without imaging evidence of acute infarction.

Strokes are to be classified as ischemic, hemorrhagic stroke, or uncertain. Hemorrhagic strokes are considered and will be reported as both bleeding events as well as stroke endpoints. The location of the bleeding can be determined from the diagnostic imaging reports.
For the duration of the study: 12 months
All-cause mortality
Tijdsspanne: For the duration of the study: 12 months

Using a binary outcome of an event or no event (Individual rates of death, all causes).
For the duration of the study: 12 months
Medication adherence
Tijdsspanne: For the duration of the study: 12 months

Reported as the number of patients self-reporting "all assigned medications were taken" "missing at least one dose of study medication", or "not able to take all of the study medications" out of the total number of medication compliance assessments done respectively
For the duration of the study: 12 months
Incremental cost-effectiveness ratio
Tijdsspanne: For the duration of the study: 12 months

We will model the prognosis of a cohort of patients receiving rivaroxaban versus apixaban. The results will be presented as incremental cost per QALY gained, incremental costs per one clinically relevant bleeding cases prevented, and incremental cost per one life year saved.
For the duration of the study: 12 months

Medewerkers en onderzoekers

Hier vindt u mensen en organisaties die betrokken zijn bij dit onderzoek.

Sponsor

Ottawa Hospital Research Institute

Medewerkers

Canadian Institutes of Health Research (CIHR)
Canadian Venous Thromboembolism Clinical Trials and Outcomes Research (CanVECTOR) Network

Onderzoekers

  • Hoofdonderzoeker: Lana Castellucci, MD, FRCPC, Ottawa Hospital Research Institute

Studie record data

Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.

Bestudeer belangrijke data

Studie start (Werkelijk)

6 juli 2021

Primaire voltooiing (Geschat)

31 december 2027

Studie voltooiing (Geschat)

31 december 2027

Studieregistratiedata

Eerst ingediend

19 november 2020

Eerst ingediend dat voldeed aan de QC-criteria

19 november 2020

Eerst geplaatst (Werkelijk)

24 november 2020

Updates van studierecords

Laatste update geplaatst (Werkelijk)

1 oktober 2026

Laatste update ingediend die voldeed aan QC-criteria

30 september 2026

Laatst geverifieerd

1 september 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Aanvullende relevante MeSH-voorwaarden

Andere studie-ID-nummers

  • COBRRA-AF

Plan Individuele Deelnemersgegevens (IPD)

Bent u van plan om gegevens van individuele deelnemers (IPD) te delen?

NEE

Informatie over medicijnen en apparaten, studiedocumenten

Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel

Nee

Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct

Nee

Deze informatie is zonder wijzigingen rechtstreeks van de website clinicaltrials.gov gehaald. Als u verzoeken heeft om uw onderzoeksgegevens te wijzigen, te verwijderen of bij te werken, neem dan contact op met register@clinicaltrials.gov. Zodra er een wijziging wordt doorgevoerd op clinicaltrials.gov, wordt deze ook automatisch bijgewerkt op onze website .

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