One aspirin a day may be enough to prevent clots after joint surgery
NCT ID NCT04295486
First seen Jun 27, 2026 · Last updated Jun 27, 2026
Summary
This study looks at whether taking 81 mg of aspirin once a day works just as well as taking it twice a day to prevent dangerous blood clots after hip or knee replacement surgery. About 5,500 adults having joint replacement will be randomly assigned to one of the two dosing schedules. The goal is to find the simplest, safest way to prevent clots without increasing side effects like bleeding.
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Study facts
What this study's own registry entry says, in plain language.
- Phase
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Phase 2
Tests whether the treatment actually works, and watches for side effects, in a larger group.
- Participants
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About 5,478 people
The number the study aims to enrol. It can still change while the study runs.
- Started
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Mar 2021
- Expected to finish
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Mar 2027
An estimate. End dates often move.
- Lead sponsor
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Other sponsor
The registry's catch-all category, for sponsors it does not file as a company, a government agency, or a research network.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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19 years and older
- Sex
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Anyone
- Healthy volunteers
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Not accepted
This study is not open to healthy volunteers. The entry requirements below say who it is open to.
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Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion criteria: * \> 18 years of age * Planning to undergo a primary total hip or knee arthroplasty Exclusion Criteria: * High risk patients for VTE as defined by: * History of venous thromboembolism * Active malignancy * Known pro thrombotic condition * BMI \> 40 * Patients requiring anticoagulation for pre-existing conditions * Patients with the contraindication for use of aspirin or nonsteroidal antiinflammatory drugs for reasons such as peptic ulcer disease, intolerance, others. * Patients not fluent in the language of the informed consent form * Prisoners * Pregnancy * Reported to have mental illness or belonging to a vulnerable population
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
How to take part
Only the study team decides who joins. These are the ways to reach them.
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The places running it
1 site. The list below names each one and where it is.
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The official record
ClinicalTrials.gov lists the study team's own contact details, including names and phone numbers. We don't republish those.
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A doctor treating you
A doctor who knows your case can contact a study site on your behalf, and can tell you whether this study is worth pursuing at all.
Contacts and locations
Locations
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University of Miami Hospital
RECRUITINGMiami, Florida, 33136, United States
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