Associates of bone mineral density in older African Americans

Objectives: To assess correlates of bone mineral density (BMD) in older African Americans. Participants: 189 women and 115 men over age 64. Methods: Variables investigated: BMD by dual X-ray absorptiometry (DXA), medications, cardiovascular disease risk factors, demographic, lifestyle factors and functional status. Variables showing univariate correlation with BMD (p≤0.1) were entered into sex-stratified linear regression models. Results: Age range 67-96 (mean 75). The mean BMD (gm/ cm² ± standard deviation) is reported for three sites. Total body: 1.03 (±0.12) in women, 1.21 (±0.11) in men. Spine: 1.05 (±0.24) in women, 1.22 (±0.26) in men. Total hip: 0.85 (±0.15) in women, 1.04 (±0.17) in men. Gender was significantly associated with BMD (t-test, p<0.001). The R ² for tested variables were highly significant only for weight. Age was only significant for total hip in women (p0.05). Each kilogram of weight change was associated with a 5.3-6.8 mg/cm² change in BMD. Conclusions: In a population-based cohort of older African Americans, average BMD was significantly greater in men than women. Weight accounted for most of the explained variability (R²) in BMD; age added little to the overall R². Lower-weight, older African-American men and women are at significantly increased risk for low BMD and, thus, likely to be at greater risk for osteoporotic fracture.