Vertebral abnormalities may predict future fracture
MedWire News: Researchers have developed a vertebral fracture risk (VFR) score that can predict future fracture risk among postmenopausal women.
The VFR score is based on anterior, middle, and posterior vertebral heights measured from vertebrae T12 to L5 in lumbar radiographs, explain Martin Lillholm (Synarc Imaging Technologies, Herlev, Denmark) and colleagues.
The researchers hypothesized that an unfractured lumbar vertebra that shows an abnormal change of one or more of these three vertebral heights is more likely to fracture or cause fractures than one which keeps within the normal range of shape variations.
They therefore constructed the computer-based VFR score using vertebral prefracture shape variations, to give a probability of sustaining a fracture on a scale of 0-1, where 1 represents a clear prevalent fracture.
The ability of the VFR to predict future fracture was then tested in a group of 126 postmenopausal women, 25 of whom sustained at least one incident lumbar fracture (cases) and 101 controls that maintained skeletal integrity during a 6.3-year follow-up period.
At baseline, none of the women displayed any sign of calcium metabolism disorders or bone disease, or took any medication known to affect bone metabolism.
Based on the single most deformed vertebra, the researchers found that the baseline VFR score was significantly higher in cases than controls, at 0.67 versus 0.35, respectively. The score was also significantly higher in the cases when the mean (M)VFR score was calculated across T12-L5, at 0.57 versus 0.41, respectively.
A median area under the receiver operating characteristic curve of 0.82 indicated that VFR separated cases from controls with a high degree of discrimination. The discriminatory ability of the MVFR score was marginally lower at 0.73.
This, say the researchers, suggests that using the most deformed vertebra produces better fracture predictions than the mean across vertebrae T12-L5.
When the researchers divided the VFR scores into tertiles, they found that patients in the highest tertile had a 35 times higher risk for fracture than those in the lowest tertile.
Writing in the journal Osteoporosis International, Lillholm and co-authors conclude that the VFR may be a "viable supplement to bone mineral density and standard risk factors to select 'fracture free but likely to fracture' subjects from a general screening population."
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By Laura Dean