Prophylaxis against venous thromboembolism after hip surgery

To the Editor. —In their recent article on venous thromboembolism after total hip surgery, Drs Imperiale and Speroff 1 present a sophisticated meta-analysis of deep venous thrombosis and pulmonary embolism (PE) rates obtained with different prophylactic options. Unfortunately, their treatment of mechanical prophylaxis is naive. They seem to be unaware that intermittent pneumatic compression (using sleeves) and static elastic compression (using stockings) are separate modalities, with different mechanisms of prophylactic action and, thus, different efficacies in preventing deep venous thrombosis or PE when used individually or in combination. And while they do distinguish stockings from pharmacologic agents when these are used separately, they arbitrarily assign patients who used stockings in combination with drugs to the group that used drugs alone. Would the results described for the low-molecular-weight heparin (LMWH) group, for example, be as good if it hadn't included patients who used graded compression stockings? The authors' failure to allow