Oct. 20, 2009 -- A diagnosis of cardiovascular disease significantly increases the risk of future hip fracture, and there may be a genetic predisposition to both conditions, a new study shows.
Ulf Sennerby, MD, of Uppsala University, Sweden, and colleagues studied records of 31,936 twins in the Swedish Twin Registry. The researchers looked at whether elderly people may be genetically predisposed to develop both cardiovascular disease and hip fractures.
Previous data have suggested that common biologic factors underlie both diseases, and the investigators wanted to determine the extent of any relationship between the diseases and genes or lifestyle factors.
Their results are reported in the Oct. 21 issue of The Journal of the American Medical Association.
The researchers note that a study that includes twins provides a framework for an ordinary group analysis while simultaneously examining whether the relation between cardiovascular events and hip fracture is explained by genetic and early environmental factors.
The twins were born from 1914 to 1944 and data on each was studied from the age of 50. Twins with cardiovascular disease and fractures were identified by the National Patient Registry from 1964 through 2005.
Among the study's findings:
• The absolute rate of hip fractures was highest after a diagnosis of heart failure or stroke. The rate was not as high following a diagnosis of peripheral atherosclerosis or ischemic heart disease, and was lowest for people without cardiovascular disease.
• Compared to people without cardiovascular disease, patients with heart failure had about a fourfold increase in hip fracture rates; individuals with a stroke had a fivefold increase in hip fracture rates.
"Identical twins without heart failure and stroke also had an increased rate of hip fracture after their co-twins were exposed to these respective diseases," the researchers write. The association was also present, but not as strong for non-identical twins.
This suggests that genes predispose people to the development of both cardiovascular disease and hip fractures, the researchers report.
In the total population studied:
• The average hip fracture rate was 12.6 per 1,000 person-years after a diagnosis of heart failure.
• The hip fracture rate also was 12.6 per 1,000 person years after a stroke, 6.6 after a diagnosis of peripheral atherosclerosis, and 5.1 after a diagnosis of ischemic heart disease.
Those numbers compared with just 1.2 per 1,000 person years for those without cardiovascular disease.
"Clinicians should be aware of the considerably increased rate of hip fracture in both sexes, especially after a recent hospitalization for [cardiovascular disease]," the researchers argue. "Genetic predisposition is probably a major determinant of the excess fracture rate."