Tranexamic acid reduces surgical transfusions without raising clot risks

A landmark clinical trial published in the prestigious New England Journal of Medicine found that tranexamic acid reduced transfusions across major surgeries without increasing the risk of dangerous blood clots. The trial was sponsored and coordinated by the University of Manitoba (UM) and co-led by researchers at UM and The Ottawa Hospital.

Tranexamic acid is an inexpensive drug that prevents excessive bleeding and stabilizes blood clots. It has been used in cardiac and some orthopedic surgeries for over 30 years, but doctors have been uncertain if it can safely be used in other major surgeries, especially cancer surgeries.

This pan-Canadian clinical trial studied over 8,000 major surgeries to determine if tranexamic acid reduced bleeding and blood transfusion without increasing the risk of clots. The results of the trial support expanding its use to all major surgeries where patients face a high risk of blood loss.

This is transformative to patient care and globally has the potential to save millions of units of red blood cells each year." 

Dr. Brett Houston, co-first author and hematologist and clinician-scientist, University of Manitoba and CancerCare Manitoba

Major surgery includes procedures of the head, chest, abdomen, or pelvis, and typically requires general anesthetic and a hospital stay. For these surgeries, more than one in 20 patients will need a blood transfusion. 

"If tranexamic acid is universally adopted across major surgeries, it will improve surgical safety for millions of patients around the world. In Canada alone, adopting this drug across the board could reduce the number of patients who need a transfusion by 25 per cent annually and reduce the number of blood units required by 10 per cent," said Dr. Daniel McIsaac, co-first author and anesthesiologist and senior scientist at The Ottawa Hospital and Clinical Research Chair in Perioperative Innovation at the University of Ottawa. 

Universal adoption of the drug also has the potential to save significant money.

"One transfusion in Canada costs more than $700 CAD, compared to under $10 for tranexamic acid. We estimate that the routine adoption of tranexamic in major non-cardiac surgeries could save 50,000 units of blood each year in Canada and millions of units around the world; the savings to health-care systems will be profound," said the trial chair and co-senior author Dr. Ryan Zarychanski, a hematologist, critical care physician, and clinician-scientist at the University of Manitoba and CancerCare Manitoba. 

To discover if tranexamic acid reduces blood transfusion without increasing the risk of blood clots, the team used a cluster-crossover trial design to randomly assign hospitals to treat patients having major surgery with high risk of blood loss to tranexamic acid or placebo. The hospitals would then switch treatment every four weeks for approximately two years. The Ottawa Hospital's Ottawa Methods Centre played a key role in designing this trial to answer the research question quickly and efficiently. 

The study team accessed hospital information on transfusions and clots directly from clinical and administrative health data sources housed in Manitoba and at ICES. They analyzed data from 8,273 major surgeries performed at 10 Canadian hospitals between February 2022 and March 2024.

The researchers found that 7.4 per cent of the patients who received tranexamic acid needed transfusions compared to 9.8 per cent in the placebo group. For every 100 patients treated with tranexamic acid, 10 units of blood could be saved. Importantly, they found that tranexamic acid did not increase the risk of venous blood clots 90 days after surgery. The rate of blood clotting in both the treatment and placebo groups was the same, at 2.1 per cent. 

One unique aspect of the study was that 60 percent, or about 5,000 participants, had surgery to remove cancer. People with cancer are often left out of these kinds of studies, even though they are a large part of the surgical population. The trial found that tranexamic acid during major surgery was safe and effective even for cancer patients, who are at a higher risk of blood clots due to cancer. 

"We hope our findings will reassure care providers that this drug is safe and effective at reducing bleeding and remove a barrier to its use in most major surgeries," said Dr. Dean Fergusson, co-senior author and Deputy Scientific Director, Clinical Research and senior scientist at The Ottawa Hospital and professor at the University of Ottawa.