Socioeconomic influences on bone health in postmenopausal women: findings from NHANES III, 1988-1994

Our objectives were (1) to examine the associations of education and income with bone health in non-Hispanic White, non-Hispanic Black and Mexican-American postmenopausal women, (2) to determine if any observed associations can be explained by behavioral factors such as calcium intake and physical activity and (3) to determine if government food assistance and education are associated with increased calcium intake among low-income women. Cross-sectional data were gathered by the Third National Health and Nutrition Examination Survey, 1988-1994 (NHANES III) using a stratified multistage probability design. Bone health was indicated by total hip bone mineral density (BMD, g/cm(2)). Multiple linear regression was used to evaluate the associations of education, income and behavioral factors with BMD. There were 2,905 postmenopausal women with acceptable DXA scans and complete relevant data selected from a nationally representative sample of the civilian non-institutionalized population aged 2 months and older. Education and income were positively associated with BMD in Black and White women, respectively, but not in Mexican-American women. When behavioral factors were included in the analyses, associations with education and income were eliminated. Instead, positive associations with estrogen use, calcium intake and physical activity, and a negative association with smoking, were noted in White women. Among low-income women, education was associated with increased calcium intake, while participation in the Food Stamp Program was associated with increased calcium intake in Black women. We conclude that education and/or income are positively associated with BMD among Black and White postmenopausal women, and that efforts to promote bone health among low-income women are warranted.