Bone test predicts long-term fracture risk

A single test of bone thickness can predict whether a woman is likely to experience backbone or vertebral fractures in the next 15 years. Bone mineral density (BMD) is a measure of bone thickness that can be determined with special X-rays (dual-energy x-ray absorptiometry - DEXA) and ultrasound. Osteoporosis, which is characterised by a low BMD, is a common disorder among older women. Women with low BMD who already have vertebral fracture are known to be at risk of new vertebral fractures during short-term follow-up but the long-term risk has not been established. American researchers studied 2,680 women, with an average age of 69 years when the study began. 394 women had X-ray evidence of at least one vertebral fracture. During the 15 years of follow-up, 42 percent of women with a previous vertebral fracture developed a new one, much higher than the 14 percent rate seen among women who had never had these fractures. After accounting for hormone use and other factors, the risk of a new vertebral fracture was increased four-fold among those with vertebral fractures when the study began. Low BMD at any body site also predicted new fractures, but BMD at the lumbar spine had the strongest association. The absolute risk of vertebral fractures was more than 50 percent among women with both a prior vertebral fracture and BMD in the osteoporotic range. For those with neither risk factor, the risk was about 9 percent. The results support the recommendation that older women with a prior vertebral fracture should be treated for osteoporosis irrespective of BMD.