Axial and appendicular bone density predict fractures in older women

TLDR

The study aimed to determine whether hip and spine bone mass measured by DEXA predicts fractures in older women and to compare its predictive value with single‑photon absorptiometry of appendicular sites. A prospective cohort of 8,134 nonblack women aged 65 and older, all of whom had both DEXA and SPA measurements, was followed for an average of 0.7 years. Fracture risk was inversely related to bone density at all sites, with relative risks per standard‑deviation decrease of 1.40 at the proximal femur and 1.35 at the spine; no site, including distal radius, proved a significantly better predictor, indicating that hip, spine, and appendicular measurements similarly predict fracture risk.

Abstract

Abstract To determine whether measurement of hip and spine bone mass by dual-energy x-ray absorptiometry (DEXA) predicts fractures in women and to compare the predictive value of DEXA with that of single-photon absorptiometry (SPA) of appendicular sites, we prospectively studied 8134 nonblack women age 65 years and older who had both DEXA and SPA measurements of bone mass. A total of 208 nonspine fractures, including 37 wrist fractures, occurred during the follow-up period, which averaged 0.7 years. The risk of fracture was inversely related to bone density at all measurement sites. After adjusting for age, the relative risks per decrease of 1 standard deviation in bone density for the occurrence of any fracture was 1.40 for measurement at the proximal femur (95% confidence interval 1.20–1.63) and 1.35 (1.15–1.58) for measurement at the spine. Results were similar for all regions of the proximal femur as well as SPA measurements at the calcaneus, distal radius, and proximal radius. None of these measurements was a significantly better predictor of fractures than the others. Furthermore, measurement of the distal radius was not a better predictor of wrist fracture (relative risk 1.64: 95% CI 1.13–2.37) than other sites, such as the lumbar spine (RR 1.56; CI 1.07–2.26), the femoral neck (RR 1.65; CI 1.12–2.41), or the calcaneus (RR 1.83; CI 1.26–2.64). We conclude that the inverse relationship between bone mass and risk of fracture in older women is similar for absorptiometric measurements made at the hip, spine, and appendicular sites.