McMaster University

McMaster University

Faculty of
Health Sciences

Few Canadians aware of dangers of thrombosis

Published: October 13, 2015
Jeffrey Weitz
Dr. Jeffrey Weitz, professor, Department of Medicine and Department of Biochemistry and Biomedical Sciences

Few Canadians realize that thrombosis, or blood clots, is behind one in four deaths, and fewer know that it is treatable and largely preventable, says a new study.

Besides the cause of heart attack and stroke, thrombosis is the cause of deadly blood clots in veins, called venous thromboembolism (VTE). These clots usually arise in the deep veins of the legs; so-called deep-vein thrombosis or DVT, where they produce leg pain and swelling. If untreated, the clots in the veins of the legs can break off and travel to the lungs to produce pulmonary embolism (PE), which can be fatal.

In Canada, just 52 per cent are aware of thrombosis, 41 per cent of DVT and 59 per cent of PE, compared with 85 to 90 per cent knowing about prostate and breast cancer, stroke, HIV/AIDS, heart attack and high blood pressure.

The finding is part of a global study commissioned by the International Society on Thrombosis and Hemostasis (ISTH) and published in July 2015 in the Journal of Thrombosis and Hemostasis, as part of awareness building for World Thrombosis Day on Oct. 13.

The study found that globally, awareness of thrombosis is 68 per cent, while those for DVT and PE are 44 per cent and 54 per cent, respectively. By comparison, awareness of the other major diseases ranges from 82 to 90 per cent. Therefore, like the situation in Canada, global awareness of thrombosis in general and DVT and PE in particular is far below that of other diseases, many of which are much less common.

"We need to make some noise about this," said Dr. Jeffrey Weitz, a professor of medicine and biochemistry of the Michael G. DeGroote School of Medicine at McMaster University and an author of the study. "People need to know about the risk factors for venous thromboembolism so that they can advocate for prevention and they need to know the symptoms and signs because early treatment can be life-saving."

Weitz is executive director of the Thrombosis and Atherosclerosis Research Institute (TaARI) of McMaster and Hamilton Health Sciences and he holds the Canada Research Chair in Thrombosis and the Heart and Stroke Foundation J.F. Mustard Chair in Cardiovascular Research. He is also an executive member of council for the ISTH.

The study showed less than one in three Canadians knew that the risk factors for VTE include hospitalization (23 per cent aware), birth control pills or estrogen replacement (28 per cent), pregnancy (27 per cent) and cancer (18 per cent), although more were aware of the risks of immobility (63 per cent aware), family history (58 per cent), older age (49 per cent) and surgery (42 per cent). Awareness in other countries ranked similarly.

Among Canadians aware of the threat of thrombosis, the majority knew the symptoms of DVT are tenderness, pain, warmth or swelling of the leg or a change of skin colour. Most Canadians knew that rapid heart rate, chest pain or shortness of breath could indicate PE. However, only 48 per cent of Canadians and 45 per cent across the global study knew that most blood clots can be prevented.

"We know patients at risk are not evaluated for thrombosis issues as often as they need to be, so people need to know their risk factors so they can alert their medical professionals," said Weitz. "As well, we know that the medications to prevent thrombosis are under-used when patients are admitted to hospital for medical or surgical conditions both here and around the world. We can do much better in preventing and treating this serious condition."

The study by Ipsos-Reid involved 800 adults in each country, including Canada, the U.S., U.K., the Netherlands, Argentina, Australia, Germany, Japan and Thailand. It was funded by the ISTH.

Valid XHTML 1.0 Transitional Level Double-A conformance, W3C WAI Web Content Accessibility Guidelines 2.0