Visual assessment of vertebral deformity by X-ray absorptiometry: A highlypredictive method to exclude vertebral deformity

The accurate identification of prevalent vertebral fractures is important i n both the clinical and research setting as they are associated with increa sed risk of further fracture and irreversible clinical consequences. This s tudy reports a direct comparison of prevalent vertebral deformity identific ation using X-ray absorptiometry (XA) scans, acquired on a dual-energy X-ra y absorptiometry (DXA) machine, and conventional radiographs in a diverse g roup of 161 postmenopausal women, ranging from healthy subjects with normal hone mineral density (BMD) to osteoporotic subjects with multiple vertebra l deformities. Deformities were identified by a trained operator by visual assessment of the XA scans (VXA) and semiquantitatively by an experienced r adiologist on the conventional radiographs (XSQ). Subjects were recruited p rospectively and were triaged according to their VXA results into normal, e quivocal and definite deformity groups. VXA and XSQ demonstrated good agree ment (96.3%, kappa = 0.79) in classifying vertebrae as normal or deformed i n the 1978 of 2093 vertebrae deemed analyzable on both the XA scans and con ventional radiographs. VXA showed good densitivity (91.3%) in the identific ation of moderate severe XSQ deformities and an excellent negative predicti ve value (95.0%) was produced when VXA was used to distinguish subjects wit hout vertebral deformities from those with possible or definite deformities on a per subject basis. The majority of disagreement between the two metho ds resulted from different classification of mild wedge and endplate deform ities and the poor visualization of upper thoracic vertebrae on the XA scan s. Agreement improved, particularly on a per subject basis, when analysis w as restricted to the vertebral levels from L4 to T7. Visual triage of XA sc ans by a trained operator would seem to be swift, convenient and cost-effec tive method, with excellent negative predictive value, to distinguish subje cts with very low risk of vertebral deformities from those with possible de formities. These 'normal' subjects can then be excluded prior to performing conventional radiographs and further time-consuming and costly methods of vertebral deformity assessment such as XSQ by an experienced radiologist an d/or quantitative morphometry. VXA may prove useful in the clinical evaluat ion of patients at risk of osteoporosis as an adjunct to BMD scans or in th e selection of subjects for osteoporosis-related clinical trials.