Objectives: To determine prospectively the rates of change in bone mineral density in elderly people and to examine the relation between lifestyle and demographic factors and these rates of change.
Design: Longitudinal population based study.
Setting: Dubbo, New South Wales, Australia.
Subjects: Representative sample (n = 769) of residents aged > or = 60 on 1 January 1989.
Main outcome measure: Rates of change in bone mineral density measured prospectively (mean scan interval 2.5 years) at the femoral neck and lumbar spine by dual energy x ray absorptiometry.
Results: Summary rates of loss in the femoral neck were 0.96% per year (95% confidence interval 0.64% to 1.28%) in women and 0.82% per year (0.52% to 1.12%) in men. Importantly, rates of loss at the femoral neck (both percentage and absolute) increased in both sexes with advancing age. No significant loss was evident in either sex at the lumbar spine, probably because of coexistent osteoarthritis. Lifestyle factors had only modest effects on rates of loss at either site.
Conclusions: These data show that bone density of the femoral neck declines at an increasing rate in elderly people, and as this site is predictive of fracture suggest that treatment to minimise bone loss may be important even in very elderly people.