Understanding the problem

People who are 75 years or older are at a higher risk for developing DVT or PE, as well as bleeding while taking anticoagulants, compared to younger people. Traditionally, this group of people would take warfarin (vitamin K antagonist; VKA) for treatment of DVT or PE. While warfarin works well, it often interacts with other medications and foods. This can make it difficult to find a safe dose that provides protection from new clots, but doesn't increase the risk of bleeding too high. For this reason, people taking warfarin need to get regular blood tests done to check how long it takes for their blood to clot (INR).

The newer anticoagulants, called DOACs, require taking 1-2 pills per day but do not require frequent blood tests. However, if people experience bleeding or require emergency surgeries, there is not as much experience with reversing the effects of DOACs on the body's clotting system as there is with reversing warfarin. Also, some people cannot safely take DOACs, such as people with mechanical heart valves, or severe kidney disease or severe liver disease. DOACs are also much more expensive than warfarin.

It is unclear which of the two drug classes, DOACs or VKAs, are better for treating acute DVT or PE in people who are over 75 years old. The authors of this review wanted to know if evidence available in the medical literature could answer this question.