Semiquantitative evaluation of prevalent vertebral deformities in men and their relationship with osteoporosis: The MINOS study

Epidemiologic studies have shown a high prevalence of vertebral deformities in men without a steep increase with aging, suggesting that a substantial number of these deformities are not related to osteoporosis. To determine w hich vertebral deformities are likely to be osteoporotic fractures, we comp ared vertebral deformities and bone mineral density (BMD) in a cohort of 78 6 men aged 51-85 years (the MINOS study). Normal vertebral height ratios we re defined in a group of 120 healthy men aged 21-50 years. We classified ve rtebral deformities by using the semiquantitative method described by Genan t et al., which was slightly modified at the level of thoracic kyphosis (T6 -T9). At that level, grade 1 wedge deformities were defined as a 25-30% dec rease in anterior vertebral height and grade 2 by a 30-40% decrease. The sa me cutoff of 49% was used for grade 3 for all vertebrae from T4 to L4. BMD was measured with a Hologic 1500 device at the lumbar spine, hip and whole body and with an Osteometer DTX 100 device at the forearm. Z-scores were ca lculated in 10-year age groups. The prevalence of vertebral deformities inc reased significantly with age. After adjustment for age and body weight, BM D did not differ between those with and without vertebral deformities. In p atients having grade 2 and 3 deformities, BMD was lower than in men having no deformities or only grade 1 deformities when adjusted for age and body w eight. Using the age- and body-weight-adjusted lest of linear trend for sex tiles of BMD, prevalence of grade 2 and 3 vertebral deformities increased w ith a decrease in BMD at all the sites of measurement. Grade 1 deformities were not correlated with BMD at any site. Among 126 patients who had only g rade 1 vertebral deformities, 32 deformities in 30 men were confirmed as ve rtebral fractures according to their morphology but their BMD did not diffe r from the nonfractured men. These findings were confirmed when vertebral d eformities were measured by the conventional morphometric method in a subgr oup of 131 men. Our data suggest that a cutoff of 30% for wedge deformities from T6 to T9 and of 25% for other deformities has a high specificity and a moderate sensitivity for identifying vertebral deformities related to low BMD in men. Grade 1 deformities are often either false positive or deformi ties related to nonosteoporotic disease of the spine.