Blood Clots - Keeping Safe through Awareness

By: Kamalvir Pablay

In January 2025, the CDC estimated that nearly 900,000 people in the United States are affected by blood clots each year. Each year, between 60,000 to 100,00 people in the US die of causes related to blood clots. Since 2010, cardiovascular diseases have become the leading cause of death worldwide, accounting for every 1 in 4 deaths. For more Canadian numbers, a 2020 study from McMaster University estimated that 13 in 10,000 people are diagnosed with blood clots each year. Putting this in perspective, of the more than 31,000 students at Queen's University, about 40 students will be diagnosed with a blood clot each year.

Blood clots are seen in people with the most unhealthy to the most healthy lifestyles. A recent example is the NBA star Victor Wembanyama, a 21-year-old athlete competing at the highest level in basketball, who was diagnosed with a blood clot in his right shoulder. He was subsequently ruled out of play for the remainder of the season. Last year in the NHL playoffs, Brock Boeser, the 27-year-old leading goal scorer for the Vancouver Canucks could not play in the team's Game 7 against the Edmonton Oilers due to blood clot-related problems.

So, blood clots sound bad, but what are they? When you have a cut or injury, blood clotting is a natural process that helps stop the bleeding by forming a barrier and allowing the body to heal the wound. However, blood clots become problematic when there is too much clotting.

Blood clots are often referred to by more technical terms. The Cleveland Clinic explains that a "'thrombus" is a blood clot, while an "embolism" occurs when a clot blocks a blood vessel. "Venous thromboembolism" (VTE) refers to blood clots in the veins and is most often what is being referred to when generally discussing blood clots. "Deep vein thrombosis" (DVT) refers to blood clots in larger veins, such as those in the arm or the leg and other lower extremities. You may have heard of pulmonary embolisms, which refer to blood clots in the veins going to the lungs. A clot in the veins can also travel to a deep vein, leading to a DVT. DVTs are often the most serious complication because the clot can break off and travel to the lungs, causing a pulmonary embolism. This can block blood flow to the lungs and therefore become fatal.

It is worth noting that we can have arterial blood clots, however, conditions related to these are dependent on other factors such as atherosclerosis, hence why discussion in the literature is primarily focused on blood clots in the veins.

The CDC has stated that oftentimes, individuals with blood clots are without symptoms. However, those with a DVT may sometimes develop swelling, pain or tenderness, warmth, redness or discolouration in the affected leg or arm. A pulmonary embolism is much more apparent and dangerous. Warning signs of a pulmonary embolism include difficulty breathing, irregular or faster heartbeat, chest pain or discomfort (worsening with deep breath or coughing), cough or coughing up blood, and very low blood pressure, lightheadedness or fainting. If you notice yourself or anyone near you with these symptoms, please look for medical attention immediately.

Some good news is that the risk factors for blood clots are well documented after decades of research. In 2023, Waheed et al. published a book describing obesity, pregnancy, individuals older than 60 years of age, surgery, hospitalization, dehydration, and cancer as well-known for their causality with blood clots. They also note that DVTs specifically are more common in individuals 40 and over. They are also more common in African Americans and caucasian populations as compared to Hispanic and Asian populations. There is also an association with DVT between hospitalization for patients undergoing surgery and conditions like cancer, congestive heart failure, and obstructive airway disease. The CDC writes that injury to a vein, low physical activity/movement, and increased estrogen levels in women are some additional factors associated with DVTs. Another big one is flights longer than 3 hours which are associated with the incidence of blood clots, especially for people shorter than 5'3" or taller than 6'3" due to leg room. Genetics also play a role in the risk of blood clotting problems.

It is important to note that blood clots are overall not very common, and are easily preventable and treatable when not severe (i.e. not a heart attack, stroke or pulmonary embolism). The CDC recommends taking breaks to walk every 1-2 hours, wearing loose clothing, exercising your legs, staying active, and maintaining a healthy weight to reduce the risk of blood clots. Compression stockings are commonly used in reducing the risk of DVT and relieving pain and swelling and are especially used for long flights. After having a DVT, they are often used for up to 2 years. Blood thinners including anticoagulation (e.g. Warfarin) or antiplatelet (e.g. Aspirin) medications are also used to reduce blood clotting. Surgery may also be used to remove blood clots.

Blood clots are regarded as among the world's most preventable causes of death. March is Blood Clot Awareness Month, making this a great opportunity to make a difference! We encourage you to share what you have learned with a friend. You could be the reason someone avoids a life-threatening complication or even saves their own life!

References:

Queen's Health Advocates

Blood Clots - Keeping Safe through Awareness

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