Abstract
Ageβrelated changes in bone density contribute to the risk of fractures. To describe the relationship between age and bone mass in elderly women, we studied a large cohort of women over age 65 years who were recruited from populationβbased lists in four cities in the United States. Bone density in g/cm^2^ was measured by singleβphoton absorptiometry (SPA) and dual xβray absorptiometry (DXA) at the distal and proximal radius, the calcaneus, the lumbar spine, and the proximal femur. Centralized data collection was used to control data quality and consistency. We found a strong inverse relationship between bone density and age for most sites. Decrements in bone density between women aged 65β69 years and women 85 years and older exceeded 16% in all regions except the spine, where the difference between the two age groups was 6%. Ward's triangle and the calcaneus exhibited the largest decrements, with 26 and 21%, respectively. The estimates of annual changes in bone mineral density by linear regression at sites other than the spine ranged from β0.82% at the femoral neck and trochanter to β1.30% at Ward's triangle. Correlations between the different regions ranged from r = 0.51 between the proximal radius and Ward's triangle to r = 0.66 between the distal radius and calcaneus. We conclude that the inverse relationship between age and bone mass measured by absorptiometry techniques in white women continues into the ninth decade of life. The relationship is strongest for bone density of Ward's triangle and the calcaneus and weakest for the spine.