Genetic factors suspected in increased hip fractures after cardiovascular events

Individuals older than 50 years old diagnosed with cardiovascular disease (CVD) demonstrated an increased risk of future hip fractures, based on a study of more than 31,000 Swedish twins.

Researchers found a significantly increased crude absolute rate of 12.6 hip fractures per 1,000 person years after the twins were diagnosed with either heart failure or stroke.

They also identified lower yet elevated hip fracture rates after diagnoses of peripheral atherosclerosis and ischemic heart disease, which had crude absolute rates of hip fracture of 6.6 and 5.2 per 1,000 person years, respectively. By comparison, the crude absolute hip fracture rate was 1.2 per 1,000 person years in twins without CVD.

Karl Michaëlsson, MD, PhD, one of the investigators for the study in the Journal of the American Medical Association, told ORTHOSuperSite.com, “There are other studies that have looked at stroke and hip fractures … but this is the first cohort study that has considered all cardiovascular events and their future risk of hip fracture.”

While the study emphasized genetic factors since it only included twins, it also explored the role of the early environmental factors that twins share in the increased risk of fracture that elderly patients with CVD have.

Michaëlsson, of Uppsala University, Uppsala, Sweden, and colleagues studied 31,936 twins born between 1914 and 1994 who were tracked in the Swedish Twin Registry. They focused on those with CVD who sustained fractures between 1963 and 2005 based on data in the National Patient Registry.

Investigators used the time from CVD diagnosis to hip fracture as their main outcome.

Twins pseudo-exposed to heart failure had a 3.7-fold increased risk for hip fracture and a 2.3 times higher risk when pseudo-exposed to stroke, according to a press release.

“It is a substantially high risk for hip fracture in these patients. If the risk is increased 4 to 5 times, they have a 10-year probability risk of hip fracture of 20%. They should be considered for an evaluation of their risk of fracture by bone scans,” Michaëlsson said.

For more information:
Karl Michaëlsson, MD, PhD, can be reached at Uppsala Clinical Research Center, Uppsala University, SE-751185 Uppsala, Sweden; +46-18-471-0000; e-mail: karl.michaelsson@surgsci.uu.se. He has no direct financial interest in any products or companies mentioned in this article.

Reference:
Sennerby U, Melhus H, Gedeborg R, et al. Cardiovascular diseases and risk of hip fracture. JAMA. 2009;302:1666-1673.