Bleeding risk evaluation before anticoagulant therapy

Dr Mark Crowther is a professor and chair of the Department of Medicine and the Leo Pharma Chair in Thromboembolism Research at McMaster University.

How to properly evaluate bleeding risk before starting anticoagulation?

Mark Crowther, MD, MSc: Bleeding risk assessments are also very interesting. The background to this is that there is no bleeding risk assessment score that predicts an individual patient’s risk of bleeding. You can calculate the risk of bleeding on a population basis, but you cannot look at one patient and say, “You will or will not have a bleed”.

There are patients who you can predict have a high risk: if they recently had a gastrointestinal (GI) bleed or if they have had certain brain lesions that predispose them to bleeding, those patients would be at high risk.

Remember, though, that when you are considering putting a person on anticoagulants, you are doing this because they have a risk of thrombosis, so it always becomes a risk-benefit equation. And you should only anticoagulate people in whom the risk of the thrombotic event outweighs the risk of bleeding. Nobody else should be anticoagulated.

So, if the patient has a very high risk of bleeding, then they probably should not receive an anticoagulant. The most extreme example of that is a patient who has an acute deep vein thrombosis with an active GI bleed. That person should not receive an anticoagulant but should have an inferior vena cava filter placed to prevent that clot from moving acutely while you address the bleeding source. Once the bleeding source is addressed, then that filter should be taken out and the patient should be put back on anticoagulant drugs.