THE COMBINED USE OF ULTRASOUND AND DENSITOMETRY IN THE PREDICTION OF VERTEBRAL FRACTURE

Measurement of ultrasonographic parameters provides information concer ning not only bone density but also bone architecture. We investigated the usefulness of ultrasonographic parameters and bone mineral densit y for evaluating the probability of vertebral fracture. 397 postmenopa usal women (59.1 +/- 6.0 years) with (n = 178) or without (n = 219) at raumatic vertebral fractures were studied. In all women, bone mineral density (BMD) of the lumbar spine was evaluated by dual X-ray absorpti ometry (DXA) and speed of sound (SOS); broadband ultrasound attenuatio n (BUA) and Stiffness in the calcaneus were evaluated by an Achilles u nit (Lunar Corporation). Ultrasonographic parameters and BMD were comp ared by examining the magnitude of the odds ratios, to determine which produces the highest estimate of the probability of odds of fracture, and by examining widths of the respective confidence intervals (CI) t o show which estimate of odd ratio is the most precise. The relative r isk of vertebral fracture, after adjusting for potential confounders, was 3.5 (CI 2.6-4.8) for BUA; 4.5 (CI 3.2-6.2) for SOS; 5.8 (CI 4.0-8. 4) for Stiffness and 7.5 (CI 4.8-11.5) for BMD. Ultrasound (US) parame ters were still significant independent predictors of vertebral fractu re, even after adjusting for BMD. The relative risk of fracture for a simultaneous decrease by 1 SD of BMD and by 1 SD of each ultrasound pa rameter was 17.3 (CI 9.4-39.6) for BMD and SOS; 18.3 (CI 8.4-30.6) for BMD and BUA and 22.1 (CI 8.9-52.7) for BMD and Stiffness. Our data su ggest that US and BMD provide complementary information which can be c ombined to improve estimates of vertebral fracture risk.