Good Old Aspirin Can Do the Trick

Aspirin comparable to traditional clot prevention therapy following total hip replacement

(RxWiki News) Successful recovery after hip replacement surgery depends on good medical care to avoid problems such as infection and blood clots. There are prescription medications to prevent blood clots, but a common over-the-counter pill may be as good a choice.

A new study compared traditional clot prevention using dalteparin injections to aspirin, a cheaper and more convenient alternative.

According to the study, aspirin was just as effective as dalteparin in preventing clots and clot-related complications following total hip replacement surgery.


Ask your orthopedic surgeon about clot prevention after surgery.


This study was conducted by David R. Anderson, MD, of Capital Health in Halifax, Nova Scotia, and colleagues to compare the clot prevention properties of aspirin and dalteparin after total hip replacement surgery.

Venous thromboembolism, a condition where blood clots form in leg veins and sometimes get dislodged, is a common complication after hip replacement surgery. These clots might then be taken by blood vessels to key organs, such as the lungs, where they can block major arteries and cause organ damage.

Anticoagulant medications, also called blood thinners, are usually administered to patients who have had hip replacement to help prevent formation of new blood clots. A common blood thinner used during the hospital stay is injection of dalteparin (brand name Fragmin).

The researchers included 778 patients in their study. The average age of the patients was 58 years. All of them had undergone total hip replacement surgery and most of them were men.

Dalteparin at a dose of 5,000 units was administered to all patients for ten days following surgery. Then the patients were randomly divided into two groups.

One group of 398 patients received dalteparin injections daily for 28 days and the other group of 380 patients received 81 mg aspirin tablets orally every day.

The patients were monitored for signs of venous thromboembolism including bleeding for 90 days.

There was not a significant difference in rates of bleeding episodes between the two groups. The rate of complications including clots in deep veins of the leg and venous thromboembolism was 0.3 percent in the aspirin group and 1.3 percent in the dalteparin group.

According to the researchers, these results showed that aspirin was not inferior to dalteparin in preventing venous thromboembolism after hip replacement surgery. The study did not demonstrate superiority of aspirin over dalteparin.

Given its low cost and greater convenience, aspirin may be considered a reasonable alternative for extended thromboprophylaxis (clot prevention) after total hip arthroplasty, wrote the researchers.

The study authors conceded that it may be premature to generalize the findings of the study. Further study in this area is required before aspirin is considered both safe and effective as a blood thinner after hip replacement surgery.

The study was funded primarily by a grant from the Canadian Institutes of Health Research and by Pfizer Pharmaceuticals, Canada. The study also received funding from Bayer HealthCare.

One of the authors received a scholarship from the Fonds de la Recherche en Santé du Québec. Some co-authors reported relationships with pharmaceutical companies including Bristol-Myers Squibb, Bayer HealthCare, Biomet, Merck, Sanofi and Novartis.

Review Date: 
June 6, 2013