Aspirin is an effective – and lower-cost – alternative to the blood-thinner warfarin when it comes to preventing blood clots after joint replacement surgery. And for the majority of patients, aspirin is the safer of the two drugs, according to a study presented at the recent American Association of Hip and Knee Surgeons annual meeting.

“There has been a huge shift toward the use of aspirin and away from using expensive drugs that [may] result in worse problems than the problem we are trying to prevent,” explains senior author Javad Parvizi, MD, director of clinical research at the Rothman Institute at Thomas Jefferson University Hospital in Philadelphia.

Following a total joint replacement, patients are often given warfarin (Coumadin) to prevent a serious blood clot called deep vein thrombosis (DVT). DVTs can break off, travel to the lungs and cause a deadly blockage there, called pulmonary embolism (PE). But Dr. Parvizi says it’s become increasingly clear that the medication also leads to increased bleeding, infections and hospital readmissions.

His recent study analyzed more than a decade of records on 28,923 patients who had joint replacement surgery at Thomas Jefferson University Hospital between 2000 and 2012. To reduce the risk of clotting, patients received either 325 milligrams (mg) of aspirin twice daily or an appropriate dose of warfarin for six weeks after surgery.

After adjusting for age, gender, health issues and type of surgery (knee or hip replacement), the researchers found that patients taking aspirin had a PE rate of 0.11 percent, compared to a PE rate of 0.67 percent in the warfarin group. In other words, patients getting warfarin were more than six times more likely to experience a PE (even though the absolute risk was still small in both cases).

The rate of DVT was also significantly lower among patients getting aspirin (0.11 percent) compared to those getting warfarin (0.91 percent). The aspirin group also had fewer wound-related problems and shorter hospital stays, but the infection rates and 90-day mortality rates were not significantly different between the two groups.

“Aspirin doesn’t result in hematoma formation or bleeding, and patients are much less likely to need re-admission or develop infection,” explains Dr. Parvizi, who says these side effects are not usually associated with aspirin but are associated with other anticlotting (also called anticoagulation) drugs. “These are very important events which we are trying to avoid and, in this day and age with limited resources in health care, it’s extremely important we use agents that are effective and less risky,” he adds.