Harvard Women's Health Watch

Compression stockings after deep-vein thrombosis: Knee-highs or thigh-highs?

Within a year or two after treatment for deep-vein thrombosis (DVT)—that is, a blood clot in the leg—up to half of patients develop a serious complication called post-thrombotic syndrome (PTS). PTS is a chronic condition that involves pain, aching, swelling, itching, skin discoloration, and in severe cases, ulcers in the affected leg. The causes aren't entirely clear but probably include residual damage and inflammation from the original clot. Obesity, older age, and inadequate anticoagulation therapy may also increase the risk. There's no cure for PTS, so prevention is especially important.

Graduated compression stockings worn for two years after treatment for a first DVT have been shown to reduce the risk of PTS by as much as 50%. ("Graduated" means the stockings are tightest at the ankles and gradually looser toward the knee and thigh.) But the most reliable studies have tested only knee high stockings, so there's been some uncertainty about the best approach. Many clinicians, for example, believe that thigh-highs provide better protection than knee-highs, especially following a DVT above the knee. Now, a multicenter trial has shown that thigh-highs are no better for preventing PTS than knee-highs and more likely to be discontinued because they're less comfortable. Results were published online Dec. 16, 2011, in the journal Blood.

The study . The trial involved 267 patients treated for a first episode of DVT at eight medical centers in Italy between October 2005 and September 2007. All were prescribed courses of anticoagulant therapy. Before leaving the hospital, they were randomly assigned to wear either thigh-high or knee-high compression hose during the day for two years. Clinicians who didn't know which stockings the patients were wearing performed regular examinations for PTS symptoms. Patients were asked to keep track of their stocking use and any side effects. They were followed for up to three years.

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