Taking a low dose of aspirin each day after hip or joint surgery reduces the risk of potentially deadly clots and blockages in blood vessels in the lungs and legs, according to a new report.
Normally, physical activity helps keep blood clots from forming, but it can take people some time to get back on their feet after having hip or joint surgery. This period of inactivity after surgery increases the risk of two conditions -- pulmonary embolism and deep-vein thrombosis.
Pulmonary embolism is a potentially life-threatening condition in which a blood clot or other substance blocks a lung artery. Deep-vein thrombosis occurs when a blood clot forms in veins deep within the legs. If a clot breaks free, it can move through the bloodstream and become lodged in an artery in the lungs.
Now, a large international study has shown that daily treatment of low-dose aspirin can reduce the risk of blood clots after surgery.
"The trial proves that aspirin prevents deep-vein thrombosis, which many doctors had been uncertain about," lead author of the study, Dr. Anthony Rodgers, of the University of Auckland in New Zealand, told Reuters Health in an interview.
"Aspirin could now provide safe, inexpensive prevention for many at-risk people who up until now were not covered -- people in the first few weeks after hospital discharge following major surgery, people with a history of deep-vein thrombosis and, perhaps most importantly, people at risk in countries where aspirin is likely to be affordable option," he noted.
In the study, more than 13,000 people in five countries undergoing surgery for hip fracture were randomly treated with either aspirin or with a placebo ("dummy") pill that did not contain any medication. The study also included more than 4,000 patients in New Zealand who were undergoing joint surgery. In both groups, treatment began before surgery and continued for 35 days. The participants were also treated with other anti-clotting drugs, such as heparin, if needed.
In the report, published in the April 15th issue of The Lancet, Rodgers and colleagues note that patients in the hip fracture group who took aspirin had a 43% lower risk of pulmonary embolism and a 29% lower risk of deep-vein thrombosis compared with patients taking placebo. In addition, aspirin reduced the rate of fatal blood clots. Eighteen people taking aspirin died from a pulmonary embolism compared with 43 in the placebo group, a 58% reduction.
Aspirin was also effective at preventing clots in people who had joint surgery. Compared with placebo, aspirin reduced the risk of pulmonary embolism or deep-vein thrombosis by 34%.
One of the risks of aspirin and other drugs that prevent blood clotting is that they may lead to increased bleeding. But overall, there were few bleeding-related deaths in hip fracture patients taking aspirin or placebo. However, people in the aspirin group were about 24% more likely than those taking placebo to need a blood transfusion to replace lost blood, according to the report.
Drs. Herve Sors and Guy Meyer, of Laennec Hospital in Paris, France, warn that it is still uncertain whether aspirin is as effective as heparin, another blood-thinner. It is too soon to recommend that aspirin should be used instead of or in combination with other drugs immediately after surgery, they write in an accompanying editorial.
Several companies that make aspirin provided aspirin and some financial support for the study.
