Researcher links COVID and clots
Ottawa researchers work on connection between virus, clotting in some victims
It is a potentially life-threatening illness that doesn't get the attention health officials say it deserves. COVID-19 could begin to change that.
The connection between COVID-19 and blood clots in some patients is shining a spotlight on thrombosis (the medical term for blood clots) at a time when health officials say there is an urgent need to raise public awareness about the condition that can be life-threatening.
Certain cancers, surgery and hospitalization are among the biggest risk factors for blood clots, which can form in the leg or the lung. Other risk factors include a family history and long periods of not moving.
But COVID-19 can also be a risk factor in a small percentage of cases.
Blood clotting is one of the unusual side effects sometimes associated with the infectious disease. The illness appears to cause changes in the blood that can lead to blood clot formation.
Ottawa Hospital researchers, who are among world leaders in thrombosis research, have been working since early in the pandemic to try to reduce the risk to patients and to better understand the connection.
In the early days of the pandemic, it was feared that a high percentage of COVID-19 patients experienced blood clotting. Researchers now believe that between five and 10 per cent of hospitalized COVID-19 patients will develop blood clots. Among patients in intensive care, the rates can be as high as 30 per cent, much higher than for the general hospitalized population.
The risk is mainly in patients who are hospitalized, not those at home, according to Thrombosis Canada.
Patients hospitalized with COVID-19 at The Ottawa Hospital already receive a low dose of blood thinner as part of their normal care. An international clinical trial is underway to find out whether a higher dose of blood thinner can improve the outcomes of patients with COVID-19.
Ottawa researchers have recruited hundreds of volunteers to participate in a study looking at which treatments work best to reduce the risk of blood clots in COVID-19 patients and improve their outcomes — the lower routine dose or a higher dose.
Dr. Lana Castellucci, an associate scientist at The Ottawa Hospital Research Institute and a thrombosis physician at The Ottawa Hospital, said researchers know a little more about the rates of blood clots in COVID-19 patients than they did at the beginning of the pandemic but are continuing to study the issue to improve treatment.
Interim results of some of that research are expected soon, she said, which should offer guidance
about whether higher doses of blood thinner help reduce risk of admission to intensive care or death.
“We continue to learn on a daily basis,” she said. “It has been really exciting.”
Castellucci said some of the findings about blood clotting in COVID-19 could potentially be ap
Researchers now believe that between five and 10 per cent of hospitalized COVID-19 patients will develop blood clots.
plied to non-COVID-19 patients or those with other infections.
COVID-19 may have raised the profile of the potential dangers of blood clots but, in general, officials say, Canadians should know more about the risk factors and warning signs.
Thrombosis affects around 100,000 Canadians a year, causing 10,000 deaths, according to Thrombosis Canada, which says it should be viewed as a health risk along the lines of high blood pressure, heart attacks and stroke.
Most Canadians understand that blood clots are serious but don't know the warning signs or understand the most serious risk factors, according to research done by Thrombosis Canada.
Thrombosis Canada has a campaign aimed at raising awareness about the common signs of blood clots using the mnemonic CLOTS for chest pain, light-headedness, out of breath, leg tenderness and leg swelling.
People who have some of those signs should see a doctor or go to the emergency department.