Description of bone mineral density distribution in women and the research of epidemiology forecast model of bone mineral density in women

OBJECTIVE: To explore the distribution of bone mineral density (BMD) with age and to depict independent effects of age, year since menopause, height and weight on BMD and then to develop predictive model based on such determinants. METHODS: 3008 pair of female twins were enrolled and their sociodemographic and envionmental data were collected with a standard questionnaire. Dual-energy X ray absorptionmetry (DPX) was used to measure subjects' BMD of all bones. Statistic analysis were done by applying SAS 6.12 and SPLUS software. RESULTS: The outcome variables studied here included BMDs of second to forth lumbar spine, total spine, femoral neck, wards' triangle, trochanter, arm and total body. Our results showed that BMDs of all sites changed with age similarly, but both the age when peak bone mass reached and the bone mass loss varied among different site. Those made of trabecular mainly reached peak bone mass earlier and began to bone mass loss earlier, and the loss rates were higher. BMD values was affected by age, years since menopause, height and weight, but the independent effect of each variables was nonlinear over the whole age range studied here; All subjects were classfied into three groups according to their age, and predictive models for each bone site were developed. These models were tested and found that the predictive values of bone mass density, obtained by these predictive model, were similar to their actual values. CONCLUSION: Our result showed that BMD values can be predicted by some easily measure variables based on the predictive models provided in this study, which provides a simple method to diagnose Osteoporosis for rural female.