Special stockings commonly given to stroke patients to prevent blood clots don't work, a new study reported Wednesday.
Doctors often prescribe the tight, thigh-high stockings to patients who have suffered a stroke, seeking to prevent blood clots in patients' legs — which could prove fatal if they break off and reach the heart or lungs.
About two-thirds of stroke patients can't walk when admitted to hospital, and up to 20 percent of those patients develop a blood clot in their legs. The stockings squash the legs and force the blood to circulate better, and can be used in place of, or alongside, anti-clotting drugs like heparin.
But in a study of more than 2,500 stroke patients in Australia, Britain and Italy, doctors found the stockings did nothing to reduce the chances of a clot. Not only that, but they caused problems like skin ulcers and blisters.
The results were simultaneously published in the Lancet medical journal and presented at the European Stroke Conference in Stockholm on Wednesday.
Some experts were surprised by the findings.
"We have used these stockings because we assume they work," said Dr. Ralph Sacco, president-elect of the American Heart Association, who was not linked to the study. "But sometimes you're surprised when you find out the truth with a randomized trial."
The stockings have been proven to reduce clots in surgery patients, so experts had long thought the low-cost solution might also help stroke patients.
In the study, about half of the patients got standard care in addition to the stockings. The other half just got standard care. Experts took an ultrasound of patients' legs after about 7 to 10 days, and then again after 25 to 30 days. About 10 percent of patients in both groups developed blood clots.
In the group wearing stockings, 5 percent reported side effects like skin problems and blisters. That compares to 1 percent in the group not given the stockings.
The study was paid for by Britain's Medical Research Council, the Scottish government, the health charity Heart and Stroke Scotland, Tyco Healthcare in the United States and the U.K. Stroke Research Network.
In Britain, draft guidelines recommend patients wear the stockings and they are used to treat an estimated 80,000 patients per year. Martin Dennis, of the University of Edinburgh and one of the study authors, said he has contacted British officials to suggest they reconsider their advice.
"This should cause a big change in how patients are treated," Dennis said, noting that in 2002, 90 percent of stroke units in Britain used the stockings.
In the United States, stockings for stroke patients are far less popular than in the U.K.
Dr. Marc Mayberg, co-director of the Seattle Neuroscience Institute, said he hadn't recommended the stockings for patients in about 20 years. He said the stockings were cumbersome and difficult for many patients, whose legs were paralyzed, to put on and take off.
Recommendations from the American Heart Association published in 2005 advised doctors to consider using the stockings in addition to an anti-clotting drug, or for patients who can't take such drugs.
Sacco said American doctors were more likely to use drugs instead of stockings to prevent clots. He thought the guidelines promoting stockings might now have to be revised.
"With this lack of effect, doctors may be much less inclined to use them," he said.