BMD at Multiple Sites and Risk of Fracture of Multiple Types: Long-Term Results From the Study of Osteoporotic Fractures

UNLABELLED: In a large cohort of U.S. women aged 65 and older, we report the relationships of BMD measured at several sites, and subsequent fracture risk at multiple sites over > 8 years of follow-up. Although we found almost all fracture types to be related to low BMD, the overall proportion of fractures attributable to low BMD is modest. INTRODUCTION: Although several studies have reported the relationship between bone mineral density (BMD) and subsequent fracture risk, most have been limited by short follow-up time, BMD measures at only one or two sites, or availability of data for only select fracture types. MATERIALS AND METHODS: In the multicenter Study of Osteoporotic Fractures (SOF), we studied the relationship of several different BMD measures to fracture risk of multiple types in 9704 non-black women aged 65 and older. We previously reported on the relationship of peripheral BMD measures to risk of several types of fracture during an average 2.2-year follow-up period. In this expanded analysis, we present results of the relationship of both peripheral and central BMD measures and fractures of multiple types during 10.4 and 8.5 years of follow-up, respectively. We also report population attributable risk (PAR) estimates for osteoporosis and risk of several types of fracture. RESULTS: Our results show that almost all types of fractures have an increased incidence in women with low BMD. However, hip BMD is somewhat more strongly related to most of the fracture types studied than spine or peripheral BMD measures. Nonetheless, the proportion of fractures attributable to osteoporosis (based on a standard definition of osteoporosis) is modest, ranging from < 10% to 44% based on the most commonly used definition of osteoporosis (BMD T-score < -2.5). CONCLUSION: Finding effective prevention strategies for fractures in older women will require additional interventions beside preventions for bone loss, such as prevention of falls and other fracture risk factors.