Screening For Osteoporosis Prevents Hip Fractures In Older Adults

The researchers found that using a machine to estimate bone density by measuring the tissues' ability to absorb X-rays was associated with a 36 percent reduction in hip fractures over six years compared with usual medical care.

The study, to be published in the Annals of Internal Medicine on Feb. 1, is a unique look at the effects of screening for osteoporosis in a general population, studying 3,107 people from the Cardiovascular Health Study (CHS). The CHS was designed to determine risk factors for cardiovascular disease in community-dwelling, older adults.

"Although some groups recommend screening for osteoporosis, no study had proven that screening prevents fractures. This study provides new evidence for the effectiveness of osteoporosis screening," says study lead investigator Lisa Kern, M.D., M.P.H., a Robert Wood Johnson Clinical Scholar at The Johns Hopkins University School of Medicine at the time of the study. Kern is now an assistant professor at the Weill Medical College of Cornell University.

"Our hope is that our study can provide a foundation on which physicians can base their medical practices regarding screening for osteoporosis, and that it can also be relevant to groups that are drafting clinical guidelines on screening for osteoporosis," says co-investigator, Neil Powe, M.D., M.P.H., M.B.A., director of Hopkins' Welch Center for Prevention, Epidemiology and Clinical Research.

According to Powe, there are two approaches to help prevent osteoporosis-related fractures. One is to promote measures that can prevent the disease itself via adequate calcium and vitamin D intake, weight-bearing physical activity, and elimination of the use of tobacco and alcohol. The second approach is to test for osteoporosis to help identify people with low bone density and then plan treatment.

To assess the benefits of screening for osteoporosis, the Hopkins team studied 3,107 men and women, age 65 and older, who were participating in CHS from 1994 to 1995. Participants already diagnosed with osteoporosis or a previous hip fracture, and those taking bisphosphonate drugs were excluded. The study included people from four states: California, Pennsylvania, Maryland and North Carolina. Participants in California and Pennsylvania had their bone density measured locally and the results were sent to their primary care doctors. Subsequent treatment decisions were left to the participants and their doctors. The researchers followed study participants for up to six years and collected information about hip fractures by using hospital records.

The Hopkins team found that hip fractures occurred in 33 screened participants (about five fractures per 1,000 person-years) and 69 usual-care participants (about eight fractures per 1,000 person-years).

"This difference is statistically significant, but there were some other differences between the groups that can partially explain the variance in the incidence of hip fracture," says Kern. "Surprisingly, differences in prescription of vitamin D, calcium, estrogen and bisphosphonates did not account for the entire difference in hip fractures."

The study did not collect information on behavior changes, such as increased physical activity or use of fall-prevention strategies, which might help account for the benefit in people who were screened. Although the study was not a randomized trial, it was the best available way to evaluate the effectiveness of screening.

"It is hard to randomize persons into screened and non-screened groups today because Medicare now reimburses for screening," says senior investigator Linda Fried, M.D., M.P.H., director of Hopkins' Center on Aging and Health. "Use of medication to enhance bone density has increased over the last 11 years, too, further making a randomized evaluation difficult. Our study has several strengths but should be useful to NIH consensus development panels and groups drafting clinical guidelines on screening for osteoporosis," adds Fried.

Current estimates of the prevalence of osteoporosis are 18 percent of women and 6 percent of men, age 50 and older.

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Funding for the study was provided by the National Heart, Lung and Blood Institute, the Robert Wood Johnson Foundation, the National Institute on Aging and the National Institute of Diabetes and Digestive and Kidney Diseases. Other researchers who took part in this study were Michael Levine, M.D., The Cleveland Clinic Foundation; Annette Fitzpatrick, Ph.D., the University of Washington, Seattle; Tamara Harris, M.D., M.S., the National Institute on Aging, Bethesda, Md.; and John Robbins, M.D , University of California, Davis.