Vertebral fracture definition from population-based data: Preliminary results from the Canadian Multicenter Osteoporosis Study (CaMos)

The Canadian Multicenter Osteoporosis Study is a large population-based pro spective study of osteoporosis In the Canadian population. The study involv es 9424 subjects, both male and female, from nine centers and seven regions of Canada. Each subject completed an extensive interview to obtain medical , demographic and lifestyle information, and was examined by dual-energy X- ray absorptiometry of the spine and hip, ultrasound of the heel and, for su bjects over 50 years of ale, lateral spine radiographs. Spinal morphometry of the initial radiographs was performed to determine the prevalence of ver tebral deformity. A method is utilized to extract reference norms for verte bral shape fi-om a subset of the population data, which is then used to cat egorize any deformity within the whole data set. Using 3 standard deviation s (SD) as a limit of normality, the male prevalence of 21.5% was similar to the female prevalence of 23.5%. Using 4 SD this reduced to 7.3% and 9.3% r espectively. The younger men (50-59 years) showed a higher prevalence of de formity than the women and a lower increase of prevalence with age. In the older age group (over 80 years) the female prevalence of 45% compared with 36% for the men using 3 SD (grade 1) to define the limit of normality. The female group presented with more severe deformities an average than the mal e group. This continuing study will provide longitudinal information regard ing the development of osteoporosis and associated risk factors which will eventually be of use to develop public health policies.