Bone mineral density alone does not predict fracture

Recently, two international studies verified what we in the Center for Better Bones have been saying for years about the fact that you cannot predict who will fracture by bone mineral density.

In a 2006 German study, it was determined that 7.8 million Germans have osteoporosis as defined by bone density.   That is, 7.8 million Germans have a bone density that is -2.5 standard deviations or more below the average bone mineral density of a young adult.  Of this total, only 4.3% were found to experience one or more clinically recognized fractures.  That is, even though millions of people have osteoporosis as defined by bone density, only 4 out of 100 of these people with osteoporosis actually experienced a meaningful fracture.

Looking at their data another way, a second group of international researchers looked at data from two large trials (the SOTI and TROPOS trials) comparing fracture incidence with bone mineral density among 6740 women.  Overall, of all the fractures that occurred in both studies, only 18% occurred in women with an “osteoporotic” bone density (that is, a bone density of equal to or greater than -2.5 SD T score).  The vast majority of women who fractured had an “osteopenia” bone density, not an “osteoporotic” bone density.

References:

Haussler, B., et al. 2007. Epidemiology, treatment and costs of osteoporosis in Germany: The bone EVA study. Osteoporosis International 18(1):77-84. (Epub ahead of print Sep 2006)

Seeman, E., et al. 2008. Strontium ranelate reduces the risk of vertebral fractures in patients with osteopenia. Jr. Bone and Mineral Research, 23(3), 433-438.