Thrombosis researchers lead revolution in diagnosing and treating deadly blood clots

July 1, 2006

Thrombosis is the formation of a clot, or “thrombus” inside a blood vessel. Deep vein thrombosis (DVT) occurs when a clot disrupts blood flow in one of the body’s deep veins, often in the legs. More than 50,000 Canadians are diagnosed with DVT every year, and in about half of these patients, the blood clot will dislodge and travel to the lungs. This is called a pulmonary embolism (PE), and it kills about a third of untreated patients. The OHRI's Thrombosis Research Group (pictured at right) is leading a revolution in the diagnosis and treatment of these deadly clots.

Research Improving Diagnosis
DVT has traditionally been very difficult to diagnose because potential symptoms are nonspecific (i.e. leg pain and swelling). The Thrombosis Research Group has developed an algorithm that assigns patients to high, low, or medium risk of DVT based on patient history and symptoms. This algorithm has improved the safety, convenience, and cost-effectiveness of DVT diagnosis around the world. They have developed a similar diagnostic algorithm for PE, which is also widely used globally. Both of these algorithms are referred to as the ‘Wells models’, after Dr. Phil Wells.

Research Improving Treatment
DVT and PE are usually treated with anticoagulants - drugs that prevent the further formation and growth of blood clots. The Thrombosis Research Group has conducted a number of studies to determine which drugs are most successful and cost-effective. They have also determined that the vast majority of DVT and PE patients can be treated at home with oral anticoagulants, rather than in the hospital. Overall, this research has led to a revolution, indeed a paradigm shift, in DVT and PE treatment. One of the next big challenges is determine to how long patients should stay on anticoagulant therapy. While a few months is likely sufficient for most patients, there may be a high-risk group who should stay on the therapy for life. This is currently under study by Dr. Marc Rodger, leader of the Thrombosis Research Group.

Research Improving Prevention
One in six Canadians has a genetic or acquired predisposition to developing DVT or PE. This is called thrombophilia. Some evidence indicates that women with thrombophilia are at even higher risk of developing blood clots during pregnancy, and that the thrombophilia puts them at risk for pregnancy complications such as miscarriage, stillbirth and low birth weight babies. The Thrombosis Research Group is currently conducting a large clinical trial to determine the safety and effectiveness of preventative use of anticoagulant therapy in at-risk pregnant women with thrombophilia.

Research Improving Understanding
The Thrombosis Research Group is currently involved in several studies evaluating the genetic causes of thrombosis including pedigree (family) studies and the creation of an extensive DNA bank. The DNA bank and the family studies will provide unique opportunities for future research.

About the Thrombosis Research Group
The Thrombosis Research Group consists of twenty clinician-researchers, students, and support staff associated with The Ottawa Hospital’s Thrombosis Clinic, the Ottawa Hospital Research Institute and the University of Ottawa. They also are part of four-university collaborative organization that conducts clinical trials in thrombosis. Visit their website for more information.