A longitudinal study of cortical bone loss in white women.

Abstract

Nursing interventions designed to prevent bone loss and fracture will have the highest risk/benefit ratio if a group of women at increased risk of bone loss can be identified. The purpose of this study was to determine the predictive ability of variables, measured prior to menopause, for cortical bone outcomes in white women twenty years later. Variables identified in the literature were related to bone outcomes in a secondary analysis of data from the Tecumseh Community Health Study. Four hundred premenopausal white women at least 30 years of age were included in this analysis. Measurements were taken from radiographic films taken at a twenty-year interval to determine cortical bone parameters in the second metacarpal. The diameter of the medullary cavity and the total subperiosteal diameter were determined. The difference in these measures, the size of the cortical bone, was further converted to percent cortical area (density). All films were measured by two individuals and the average of the measures was utilized. Premenopausal cortical bone measurements were more predictive of cortical bone measurements twenty years later than any combination of life style or body composition variables. This finding supports screening of women prior to menopause to determine those at greatest risk for fracture to be targeted for nursing interventions. The manifest variables significantly related to bone loss (change in percent cortical area) were number of cigarettes smoked, age at menopause, alcohol intake, height, income and number of pregnancies. However the regression analysis did not significantly predict bone change. Using partial least squares analysis, the latent variable groups of socioeconomic status (education and income), predetermined physical size (height and bony chest breadth), and life style (dietary variables, heart rate, smoking, alcohol, pregnancies, fatness variables) were correlated with bone loss (r = 0.22) and with the bone size measurements in 1962 and 1985 considered together (r = 0.39). The lifestyle latent variable grouping contains factors amenable to nursing intervention.