Predictive value of total body bone mineral density for vertebral fractures in elderly women. Geriatric Study Group

In a general population-based geriatric disease survey in Taipei City, the bone mineral density (BMD) of 58 women over 65 years of age was measured for the whole body, lumbar spine (L2-L4), and proximal femurs using a 153Gd based dual photon absorptiometer. These women were found to have at least one vertebral fracture. The results showed that the BMD readings of both the lumbar spine (L2-L4) (mean Z score +/- SEM = 0.05 +/- 0.12) and the femoral neck (mean Z score +/- SEM = -0.20 +/- 0.10) were not statistically different from those of age-matched controls. However, the total body BMD in these 58 patients was significantly lower than in the normal controls (mean Z score +/- SEM = -1.07 +/- 0.10, p < 0.0001). In the normal control group (N = 69, age 50-85), there was a significant linear correlation between the total body and lumbar BMD (r = 0.81, p < 0.0001). This correlation was not found in the 58 women with vertebral fractures (r = 0.14, NS). Our results suggest that geriatric women with vertebral fractures are more osteoporotic than normal aged women, even though they have a relatively mild degree of spinal osteoporosis. But, because of age-associated degenerative changes or other factors, conventional anteroposterior lumbar BMD measurements cannot detect the difference. The total body BMD readings, but not the lumbar or femoral neck BMD readings, seem to be less affected by these local changes and may provide a better discriminative or predictive value for vertebral fracture in this particular age group.