Randomized clinical trial of low molecular weight heparin with thigh-length or knee-length antiembolism stockings for patients undergoing surgery

Background: This was a randomized clinical trial to determine the efficacy and safety of a 'blanket' protocol of low molecular weight heparin (LMWH) and the best length of antiembolism stocking, for every patient requiring surgery under general anaesthesia. Methods: Of 426 patients interviewed, 376 agreed to be randomized to receive one of three types of stocking: thigh-length Medi thrombexin(R) climax(TM) (Medi UK, Hereford, UK), knee-length thrombexin(R) climax(TM) and thigh-length Kendall T.E.D.(TM). (Tyco Healthcare UK, Redruth, UK). All patients received LMWH thromboprophylaxis. Duplex ultrasonography was used to assess the incidence of postoperative deep vein thrombosis (DVT). Results: No postoperative DVT occurred in 85 patients at low or moderate risk. Nineteen DVTs occurred, all in the 291 high-risk patients: two with the Medi thigh-length stockings, 11 with the Medi knee-length stockings (odds ratio 0.18 (95 percent confidence interval 0.04 to 0.82); P = 0.026) and six with the Kendall T.E.D(.TM) thigh-length stockings. No patient developed a pulmonary embolism. Stocking groups were similar for age, sex, thromboembolic risk, type of operation and compliance. One significant bleeding complication occurred. Conclusion: A single protocol comprising LMWH and thigh-length stockings abolished DVT in low- and moderate-risk patients, and reduced the rate of DVT to 2 per cent in high-risk patients.