Quantitative ultrasound and bone densitometry to evaluate the risk of nonspine fractures: A prospective study

The ability of quantitative ultrasound (QUS) to estimate the risk of osteop orotic fractures was evaluated in a prospective study over a mean time of 5 .47 years in 254 postmenopausal women (mean age 58.06 +/- 7.67 years). Base line measurements of ultrasound transmission velocity (UTV) and bone minera l density (BMD) were taken at the distal radius (DR). UTV was also measured at the patella (P). Fifty nonspine fractures due to minor trauma were dete cted during annual check-ups with an incidence of 3.59/year. Fractures occu rred in older women with a lower BMD and QUS. Using Cox regression analysis the relative risk (RR) per 1 standard deviation (SD) decrease in the unadj usted QUS and BMD measurements was: BMD-DR = 3.56, 95% confidence interval (CI) 1.57-8.09; UTV-DR = 5.35, 95% CI 2.07-13.83; UTV-P = 4.49, 95% CI 2.08 -9.68. The relationship between BMD and QUS variables and fracture risk per sisted after adjusting for potential confounders apart from previous fractu res, giving the following RR: BMD-DR = 2.99, 95% CI 1.06-8.41, UTV-DR = 3.6 9, 95% CI 1.18-11.49; UTV-P = 3.89, 95% CI 1.53-9.90. Correcting also for p revious fractures, only UTV-P remained an effective predictor of fracture r isk even after QUS measurement correction for BMD. Wrist fractures were bes t related to BMD-DR (RR 7.33, 95% CI 1.43-37.50) and UTV-DR (RR 10.94, 95% CI 1.10-108.45), while hip and ankle fractures were significantly associate d only with UTV-P (hip: RR 32.14, 95% CI 1.83-562.80; ankle: RR 17.60, 95% CI 1.78-173.79). The combined use of BMD and QUS is a better predictor of f racture risk than either technique used separately. Comparison of the areas under the receiver operating characteristic (ROC) curves did not show diff erences in the ability of BMD and QUS to correctly distinguish fractures. I n conclusion, QUS predicts fracture risk in osteoporotic women at least as well as BMD. UTV-DR and BMD-DR are good predictors of wrist fractures, whil e UTV-P is strongly related to hip and ankle fractures. QUS and BMD combine d improve the diagnostic ability of each technique individually.