Risk factors for osteoporosis: Prevalence, change, and association with bone density

Objectives: To describe the prevalence of risk factors for osteoporosis in a population-based cohort of Australian-born midlife women; determine the e ffect of these risk factors on premenopausal and early perimenopausal bone mineral density (BMD); and describe changes in risk factors and any effect of these on bone loss. Design: S-year longitudinal community-based study. BMD of the lumbar spine (LS) and femoral neck (FN) was measured using dual x-ray absorptiometry (DX A). Setting: Melbourne, Australia Participants: 224 Australian-born women aged 46-56 years Main Outcome Measures: Risk factors for osteoporosis, LS-BMD, FN-BMD, and c hange in risk factors and BMD. Results: At baseline, 52% reported a calcium intake of less than 800 mg/day and 46% reported a caffeine intake of more than 360 mg/day; 29% exercised less than 1.5 hours/week; 5% had a body mass index (BMI) of less than 20; 1 4% were current smokers; 23% were past smokers; 10% reported abnormal menst rual histories; and 25% reported a family history of osteoporosis. BMD was positively associated with weight; BMI; and waist, hip, and trunk skin-fold measure (P < .0005). At 4-year follow-up, there were increases in weight ( P < .0005), waist/hip ratio (P < .05), trunk skin-fold measurements (P < .0 05), and calcium intake (P < .05). In women who became late perimenopausal or postmenopausal, bone loss was associated with time in relation to the fi nal menstrual period but not with other variables. Conclusions: There are multiple risk factors for osteoporosis in this Austr alian-born population of midlife women, but only anthropometric variables w ere associated with BMD at baseline. Significant changes during the menopau sal transition in anthropometric variables and calcium intake were in the d irection that could decrease the risk of osteoporosis but were not found to affect menopausal bone loss.