Bone loss in normal British women; a 5 year follow-up

To assess the rates of loss, forearm and spinal bone mineral were remeasured in 16 out of 18 peri- and post-menopausal women aged 45 to 60 years who had taken part in a previously reported cross-sectional study. The mean interval between measurements was 4.8 years (range 4.2-5.3 years). The mean (95% confidence interval (CI)) annual change in radial bone mineral density was -0.78%/year (-1.73 to +0.18%; not significant) and in spinal bone mineral -2.41%/year (-3.55 to 1.27%; p < 0.001). There was considerable variation in the rate of change in radius and spine, and between individuals. There was no significant correlation between rates of bone loss at either site, or between rates of loss and the initial bone density at either the radius or spine. There was no significant correlation between the rates of change and the age or number of years post-menopause of the women. There was no significant change in the Z score for the forearm (mean -0.20; 95% CI -0.65 to +0.25) or for the spine (mean -0.04; 95% CI -0.30 to +0.22). There have been no previous longitudinal studies of the changes of bone density in normal British women. These results show considerable variation between individuals, and rates of change at one site cannot be predicted from measurements at another site. Untreated, some normal individuals have high rates of loss that cannot be predicted from baseline values, age or number of years post-menopause.