Bone mass and subsequent risk of hip fracture

We examined prospectively the associations of bone density and bone dimensions with risk of hip fracture using data from the first National Health and Nutrition Examination Survey and its three follow-up studies. A cohort of 1,489 white women age 45 years or older who received detailed medical examinations in the baseline survey in 1971-1975 were subsequently contacted in 1982-1984, 1986, and 1987. Bone density and hand bone dimensions at several sites were measured at baseline. Fifty incident hip fractures were identified during the follow-up studies. Using Cox regression analyses, we found a relative risk of 11 for women with bone density below the 5th percentile, compared with those above the 75th percentile (95% confidence interval = 2.2-58). Women with smaller external bone dimensions also faced increased risk of hip fracture (relative risk = 4.6 for dimensions below the 5th percentile vs above the 75th percentile; 95% confidence interval = 1.5-14). On the other hand, internal bone dimensions were not associated materially with hip fracture.