Patient Safety and Quality

Medications to prevent blood clots after major orthopedic surgery are underused, especially in Japanese patients

Patients undergoing major orthopedic surgery such as hip fracture repair, hip replacement, or knee replacement are at the highest risk for developing a blood clot in the veins of the legs or pelvis (deep vein thrombosis, DVT). These clots can break off and travel elsewhere to block an artery (thromboembolism), which can be life-threatening. Practice guidelines recommend prophylactic use of anticoagulants such as heparin or warfarin after major orthopedic surgery to decrease the risk of DVT. Despite these recommendations, use of preventive anticoagulants after major orthopedic surgery is low, especially among Japanese patients.

Researchers, supported by the Agency for Healthcare Research and Quality (HS11627), conducted a retrospective study of 1,811 adults who underwent hip replacement, hip fracture surgery, or total knee replacement at a hospital in Hawaii. They found that only half of patients studied received anticoagulants to prevent thromboembolism following major orthopedic surgery. Japanese patients were 30 percent less likely to receive prophylactic therapy, after adjustment for patient age, sex, thromboembolism and bleeding risk factors, type of surgery, and anesthesia. The reason for the treatment differences was not clear. However, some studies have suggested there is a lower risk of venous thromboembolism among Asians and Pacific Islanders, and doctors may be aware of this. It also remains unclear if lower prophylaxis translated into higher rates of postoperative venous thromboembolism in this group. Other ethnic groups were treated similarly to whites.

Compared with patients undergoing hip replacement, those with hip fracture surgery (who are perceived to be at higher bleeding risk) were 60 percent less likely and those undergoing total knee replacement were over 4 times more likely to receive appropriate prophylaxis. The low overall rates of venous thromboembolism prophylaxis suggest that doctors may be unaware of the guidelines for or the efficacy of prophylaxis, note the researchers.

More details are in "Patient ethnicity and use of venous thromboembolism prophylaxis," by Rebecca P. Gelber, M.D., M.P.H., and Todd B. Seto, M.D., in the International Journal of Equality in Health Care 18(1), pp. 23-29, 2006.

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