Predicting The Risk Of Hip Fracture In Postmenopausal Women

The estimated 329,000 hip fractures that occur annually in the United States are associated with a high rate of illness and death and high cost. Prevention of hip fracture is a high priority for patients, physicians, and public health, according to background information in the article.

John Robbins, M.D., of the University of California at Davis School of Medicine, Sacramento, and colleagues evaluated clinical risk factors for hip fracture in postmenopausal women to create a predictive model for the 5-year risk of hip fracture. The study included data on a total of 93,676 women who participated in the observational component of the Women's Health Initiative (WHI), a multiethnic study.

Factors were identified that were predictors of hip fracture, which were then validated using data on 68,132 women who participated in the clinical trial. The model also was tested in a subset of 10,750 women who had undergone dual-energy x-ray absorptiometry scans (DXA; an imaging technique) for bone mass density assessment, which is used to predict risk of hip fracture.

During an average follow-up of 7.6 years, 1,132 hip fractures were identified among women participating in the observational study (annualized rate, 0.16 percent), while during an average follow-up of 8.0 years, 791 hip fractures occurred among women participating in the clinical trial (annualized rate, 0.14 percent).

Eleven factors were identified that were predictive of hip fracture within 5 years. These factors were age, self-reported health, weight, height, race/ethnicity, self-reported physical activity, history of fracture after age 54 years, parental hip fracture, current smoking, current corticosteroid use and treated diabetes. Incorporating these factors into a clinical algorithm was useful to predict the 5 year risk of hip fracture among postmenopausal women of various ethnic backgrounds.

"Further studies are needed to define the clinical implications of this algorithm and to confirm treatment benefits for those delineated by the WHI risk classification to be an increased risk for hip fracture. Ultimately, the decision of whom to further screen for osteoporosis and whom to treat will need to be based on available resources and major social and political judgments."

"Knowing the 5-year risk of fracture will permit patients and physicians to make informed choices when balancing making lifestyle changes against undergoing medical interventions. Publication of these results, along with the user-friendly tool for their application, will permit others to rapidly test their utility. However, we believe 11 readily available clinical variables offer a simple means of stratifying the 5-year risk of hip fracture in postmenopausal women," the researchers conclude.

Journal reference: JAMA. 2007;298(20):2389-2398.