Extended Use of Blood Thinners: For Whom?

Current practice in U.S. hospitals is for doctors to prescribe low doses of blood thinning medication to certain patients to protect them from getting a blood clot in their veins or lungs while they recover from their illness. The decision to give these medications is based on a combination of known risk factors that predispose a patient to form these clots while they are being treated for a specific illness. In addition to obesity and congestive heart failure, the actual reason for hospitalization, the type of surgery (if planned) and the presence of a malignancy are all issues that have to be considered when giving blood thinners. Also, a particular patient’s risk of internal bleeding from use of these blood thinners is factored in to the decision to prescribe these blood thinner medications to a hospitalized patient.

Up until recently, it was assumed that once a patient is discharged from the hospital the risk of blood clots abates and consequently these blood thinners are usually discontinued. Over the past 5-8 years, numerous studies have been published which looked at a variety of types of surgical as well as medical patients, specifically reporting when a blood clot in a vein was diagnosed with respect to postoperative day, last day of blood thinner medication or hospital discharge date. The findings are surprising. As a whole, about 30-50% of blood clots were diagnosed after blood thinners were discontinued and nearly 20% were diagnosed beyond 30 days after surgery. Aside from joint replacement patients, few other patients are routinely discharged on these medications. So, who should receive an extended course of these blood thinners after leaving the hospital?

Currently, many U.S. hospitals are using a risk scoring system (Caprini Score) when the patient is discharged to determine if and for how long blood thinner use should be extended. There is growing evidence that a Caprini score at discharge of 7-8 should provoke serious consideration for extending the use of blood thinners for at least 30 days and a score >8 should compel their use. The fact that several studies have reported that 1/3 of blood clots in veins are diagnosed after hospital discharge and that even larger studies have identified cancer surgery of GI, Lung, Ovarian/Uterine and prostate tissues being especially strong links to post discharge blood clots, it begins to get clearer who should be offered extended treatment.

Finally, it seems many of these higher risk groups can have a blood clot develop in a vein well beyond the customary postoperative period. An ongoing national registry in Spain has recently published that 20% of postoperative blood clots in veins occurred after day 30.

In summary, extended blood thinner use should be prescribed at discharge to high risk patients using a risk scoring system. Patients who undergo major abdominal or pelvic surgery, especially for cancer as well as those who need joint replacement or lower extremity fracture repair are at high and prolonged risk for venous blood clots.

What is more disturbing is that a substantial period of this risk continues after the hospitalization. Therefore, your doctor may send you home on a blood thinner medication, and if he or she does, it is for good reason.