Preventing Blood Clots: Overdone?

One of many new “quality metrics” applied to the care of hospitalized patients is the tracking of efforts to prevent blood clots from developing in the veins of recovering surgical patients. We know that surgical and trauma patients are exposed to the risk of these clotting events and while they often are not fatal, these events can be a source of morbidity, suffering and added cost. We know that air-compression devices for the legs as well as blood thinner medications reduce the chances for these complications. We have also developed a sophisticated and validated tool to preoperatively estimate the blood clot risk for a particular surgical patient. This tool is called the Caprini DVT Risk Score and is available to all doctors, even as a smart phone app (Caprini DVT Risk Score-iTunes store).

I realized though there is a problem with all of this. It occurred to me that I never knew to what degree all the clot prevention measures worked and based on the Caprini Score, when they should be used.

Surgeons at the Universities of Utah and Michigan recently tried to answer this question. I think they did a good job. In studying a group of 14, 776 patients, they discovered that the benefit of blood thinners was restricted to those with a Caprini DVT Risk score of 7 or higher. Patients with Caprini scores of 6 or less made up 75% of the overall surgical population and these patients experienced no significant blood clot reduction with blood thinners.

The tempting conclusion is that the majority of surgical patients receiving blood thinners to decrease the risk of blood clots do not need them and that at a minimum we have been wasting a lot of money. However, a more refined conclusion is that for the highest risk groups there is benefit and that until a better study shows that there is no benefit of blood thinners for those with Caprini scores less than 7, a total abandonment of blood thinners for the mid to low risk surgical patient is unwarranted.

My guess though is that changes to the guidelines for blood thinners in surgical patients will come soon.