Predictive value of low BMD for 1-year fracture outcomes is similar for postmenopausal women ages 50-64 and 65 and Older: results from the National Osteoporosis Risk Assessment (NORA)

Abstract

The relationship of low bone mass and fracture in younger postmenopausal women has not been extensively studied. In a large cohort of postmenopausal women > or =50 years of age, we found the relationship of BMD measured at peripheral sites and subsequent 1-year fracture risk to be similar between women <65 and those > or =65 years of age.

Introduction: Low bone mass and fractures are prevalent in older postmenopausal women. However, the frequency of low bone mass and fracture in younger postmenopausal women has not been studied extensively. There are very limited data regarding the association between BMD measurements and fractures in postmenopausal women who are between the ages of 50 and 64.

Materials and methods: In the National Osteoporosis Risk Assessment (NORA) we studied the frequency of low bone mass and its association with fracture in women 50-64 years of age in comparison with women > or =65 of age. NORA enrolled 200,160 postmenopausal women > or =50 years of age who had no prior diagnosis of osteoporosis. Baseline BMD was measured at the heel, forearm, or finger. A 1-year follow-up survey requesting incident fractures since baseline was completed by 163,935 women, 87,594 (53%) of whom were 50-64 years of age. The association between BMD and fracture was assessed using logistic regression, adjusted for important covariates.

Results: Thirty-one percent of women 50-64 years of age had low bone mass (T scores < or = -1.0) compared to 62% of women > or =65 years of age. During the first year of follow-up, 2440 women reported fractures of wrist/forearm, rib, spine, or hip, including 440 hip fractures. Nine hundred four women 50-64 years of age reported fractures, including 86 hip fractures, accounting for 37% of fractures and 20% of hip fractures reported in the entire NORA cohort. Relative risk for osteoporotic fracture was 1.5 for each SD decrease in BMD for both the younger and older groups of women.

Conclusion: Low BMD in younger postmenopausal women 50-64 years of age showed a 1-year relative risk of fracture similar to that found in women > or =65 years of age.