Vertebral fracture assessment (VPA) with a densitometer predicts future fractures in elderly women unselected for osteoporosis

Abstract

Low radiation dose imaging of the lateral spine acquired with a bone densitometer for vertebral fracture assessment (VFA) has great potential for clinical use. We have undertaken an evaluation of VFA in a prospective population cohort of elderly women to examine the prevalence of vertebral fractures, their ability to predict incident fractures, and their use in targeting therapy. Women (n = 5157) ≥75 yr of age living in the general community in the United Kingdom underwent posteroanterior and lateral imaging of the spine (T4-L4) with a densitometer (Hologic QDR4500A) at entry to a randomized, double-blind, controlled trial of 800 mg oral clodronate (Bonefos) or matching placebo daily over 3 yr. The women were identified from general practice registers and recruited by letter of invitation regardless of skeletal status. The proportion of vertebrae interpretable varied from 98.2% at T12 to 57.1% at T4, with >92% interpretable at levels between T8 and L3. As judged by BMD at the total hip, 19.6% of the women had osteoporosis, and the prevalence of vertebral fracture was 14.5%. Women with one or more vertebral fractures had a relative risk (RR) for incident osteoporotic fractures of 2.01 (95% CI, 1.64-2.47). The RR for hip fractures was 2.29 (95% CI, 1.63-3.21). After adjustment for age, femoral neck BMD, weight, and treatment, the RR was 1.50 (95% CI, 1.21-1.86) for osteoporotic fractures, with similar results for hip fractures (RR, 1.41; 95% CI, 0.99-2.02). For women with two or more vertebral fractures, the adjusted RRs were 1.97 (95% CI, 1.24-2.72) and 1.86 (95% CI, 1.14-3.03) for osteoporotic and hip fractures, respectively. We conclude that VFA can frequently detect vertebral fractures in a population cohort of elderly women. These fractures, like radiographic fractures, predict future clinical fractures independent of age, weight, and BMD. Having multiple vertebral fractures was associated with greater risk of incident osteoporotic fractures and hip fractures. © 2008 American Society for Bone and Mineral Research.