Women With Lupus at Higher Risk for Hip Fractures?
Study followed nearly 15,000 patients for 6 years
By Kathleen Doheny
THURSDAY, July 4 (HealthDay News) -- Women with lupus -- the autoimmune disease that can damage skin, joints and organs -- also are at higher risk of a hip fracture known as a cervical fracture, new research from Taiwan suggests.
Dr. Shu-Hung Wang, of the Taipei Veterans General Hospital, and his colleagues evaluated nearly 15,000 adults -- 90 percent of them women -- who had lupus. They followed them for an average of six years.
During that time, 75 suffered a hip fracture. Of those, 57 were cervical fractures of the hip; the other 18 were trochanteric fractures of the hip.
"Anatomically, cervical hip fractures involve the [uppermost area of the thighbone]," said Dr. Shu-Hung Wang, a rheumatology fellow at the hospital and a co-author of the study. "Trochanteric hip fracture occurs between the lesser and greater trochanters." Trochanters are the bony prominences near the end of the thighbone.
The researchers compared the women and men with lupus to the same number of healthy people without lupus. In the healthy group, 43 had hip fractures during the follow-up period, and they were evenly divided between the two types.
Having lupus, the researchers concluded, raised the risk for cervical fractures compared to the general population, but not for the other fracture type. And women with lupus got cervical fractures at younger ages, the researchers said.
Not enough men were included in the study to do a scientific analysis of their fracture risk.
The study, which didn't prove that lupus leads to hip fractures, appeared online recently in the journal Arthritis Care & Research.
The number of people studied lends strength to the findings, said Dr. David Pisetsky, a professor of medicine at the Duke University School of Medicine and a member of the scientific advisory board for the Lupus Research Institute. Pisetsky reviewed the findings but was not involved in the study.
"When you get 15,000 [subjects], you get confidence in the numbers," he said.
The higher risk of hip fracture is not surprising, due to the nature of the disease, he said. Lupus involves a malfunction of the immune system. Normally, the immune system makes antibodies in response to invaders; in lupus, the body can't differentiate invaders from normal tissue, so it makes autoantibodies that turn on the body, attacking normal tissue.
The autoantibodies cause inflammation, pain and damage to the body.
"The systemic inflammation affects bone," Pisetsky said. Patients often are prescribed steroid medicine to relieve the inflammation, but the medicines can also affect bones adversely, he said.
Although the risk to bones in lupus patients is known, the new study teases out details on the type of fracture risk, Pisetsky said.
Treatments, especially the steroids, can affect the bones, said Dr. Joan Merrill, medical director of the Lupus Foundation of America and chairwoman of the clinical pharmacology research program at the Oklahoma Medical Research Foundation. "Steroids are also associated with increased risk for osteonecrosis [death of the bones], which literally can cause the hip joint and other joints to collapse," she said.