Genes May Link Hip Fractures and Heart Disease
TUESDAY Oct. 20, 2009 -- People with cardiovascular conditions such as heart failure and stroke -- and probably their close relatives as well -- may have an increased risk for hip fractures, a new study has found.
Genetic factors might explain the relationship, including "specific genes involved in cellular mechanisms shared by the vasculature [blood vessels] and bone," said Dr. Karl Michaelsson, an associate professor of medicine at Uppsala University in Sweden and an author of a report on the finding in the Oct. 21 issue of the Journal of the American Medical Association.
The study, which involved 31,936 twins in the Swedish Twin Registry, found more than a fourfold increased risk for hip fractures for people who had heart failure, which is a progressive loss of the heart's ability to pump blood, and about a fivefold increased risk for those who'd had a stroke, compared with people with no diagnosis of cardiovascular disease. An increased risk was also found for people with other heart conditions, such as blocked coronary arteries.
The researchers also found that if one twin had a cardiovascular condition, the other twin also faced an increased risk for hip fracture -- even if that twin was healthy. They described those individuals as "pseudoexposed," meaning that because they are twins, they share the genetic factors that increase the risk for fractures.
For instance, hip fracture risk was 3.7-fold higher for a healthy twin whose twin had heart failure and 2.9-fold higher if the twin had had a stroke.
The finding means that anyone with a close relative, such as a brother or sister, with cardiovascular disease should be aware of a probable increased risk for hip fractures, Michaelsson said.
"I recommend to them to have their fracture risk evaluated by a bone scan to assess bone mineral density and a clinical examination by a physician with special interest in the problem of osteoporosis," he said.
Osteoporosis is the gradual weakening of bone generally seen in older people and usually of greater concern for women.
But osteoporosis is often overlooked in men, just as cardiovascular disease can be in women, said Dr. Lori Mosca, director of preventive cardiology at New York-Presbyterian Hospital/Columbia University Medical Center.
"The important message I took away from this as a clinician is that if you have a patient with cardiovascular disease, they may be at risk for fractures, and it is important to look at their risk factors for both," Mosca said.
The Swedish study is the latest entry in "a growing body of evidence that links osteoporosis and cardiovascular disease," she said. "There is a lot of interest in understanding a possible common pathway."
Lifestyle factors that contribute to both osteoporosis and cardiovascular risk include nutrition, smoking and lack of exercise, Mosca said. "What is unique about this particular study is that it evaluates the potential for both lifestyle factors and genetic factors to contribute to pathology," she said.
More research is needed, however, to identify the specific genetic factors linking the two risks, Mosca and Michaelsson said. "I do think this is possible, and we are on our way to performing such an investigation," Michaelsson said.
The Swedish study was possible because of a registry that includes twins born in the country between 1914 and 1944 and followed for decades. Another national registry identified Swedish twins diagnosed with cardiovascular disease and fractures between 1964 and 2005.
A limitation of the study, though, is that it covers just one ethnic group, Michaelsson acknowledged. "We cannot directly generalize our results to other ethnic groups," he said.
The U.S. National Institute of Arthritis and Musculoskeletal and Skin Diseases has tips on bone health.
Posted: October 2009