Evaluation of vertebral fracture assessment by dual X-ray absorptiometry in a multicenter setting
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The utility of vertebral fracture assessment (VFA) by DXA to detect prevalent vertebral fracture in a multicenter setting was investigated by comparison to conventional radiography. While limited by lower image quality, overall performance of VFA was good but had a tendency to miss mild prevalent fractures.
In osteoporosis clinical trials standardized spine radiographs are used to detect vertebral fractures as a study endpoint. Lateral spine imaging with dual X-ray absorptiometry (DXA) scanners, known as vertebral fracture assessment (VFA) by DXA, presents a potential alternative to conventional radiography with lower radiation dose and greater patient convenience.
We investigated in a multicenter setting the ability of VFA to detect fractures in comparison with conventional radiography. The study examined 203 postmenopausal women who had imaging of the spine by DXA and radiography. Three radiologists experienced in vertebral fracture assessment independently read the VFA scans and radiographs using the Genant semiquantitative method on two occasions.
Analyzing the data from all readable vertebrae, the kappa statistic, sensitivity, and specificity ranged from 0.64–0.77, 0.65–0.84, and 0.97–0.98, respectively. Considering only moderate and severe fractures improved the kappa statistic (0.80–0.91) and sensitivity (0.70–0.86). While image quality of VFA is inferior to radiography, the detection of vertebral fractures using visual scoring is feasible. However, VFA underperformed due to unreadable vertebrae and reduced sensitivity for mild fractures. Nevertheless, VFA correctly identified most moderate and severe vertebral fractures. Despite this limitation, VFA by DXA provides an important tool for clinical research.
KeywordsDual X-ray absorptiometry Osteoporosis Semiquantitative assessment Vertebral fracture
The authors wish to acknowledge Diane Krueger (University of Wisconsin–Madison) and the study nurses and technologists for assistance in data acquisition and preparation as well as the study participants who volunteered to participate in this research.
The collection and central review of radiographs and VFA scans was supported by Eli Lilly and Co.
Conflicts of interest
Doctors Fuerst, Wu, Genant, von Ingersleben, and Chen are employees and shareholders of Synarc, Inc. Dr. Mitlak is an employee and shareholder of Eli Lilly and Company. No other disclosures.