The relationship between bone density and incident vertebral fracture in men and women

Bone mineral density (BMD) is an important predictor of future fracture risk in women; however, there are few prospective data in men. The aim of this analysis was to determine whether there are differences in the relationship between BMD and incident vertebral fracture in men and women. Men and women were recruited from population-based registers in 21 European centers. Those recruited were interviewed and had spinal radiographs performed. The radiographs were assessed morphometrically and prevalent vertebral deformity was defined using the McCloskey-Kanis method. Repeat spinal radiographs were performed at a mean of 3.8 years after the baseline radiographs. Incident fractures were defined using a combination of the point prevalence and 20% reduction in vertebral height (plus a 4-mm reduction in absolute height) criteria. BMD measurements were made in a subsample of those recruited. Poisson regression was used to explore the influence of gender, age, prevalent deformity, and BMD on the incidence of vertebral fracture. Thirty-four hundred sixty-one men and women had both paired spinal radiographs and bone density measurements performed. BMD at the spine and femoral neck was higher in men than in women. After adjusting for age, the risk of incident vertebral fracture was greater in women than in men (relative risk [RR] = 2.3; 95% CI, 1.5-3.6) and increased by a factor of 1.4 (95% CI, 1.2-1.8), 1.5 (95% CI, 1.2-1.8), and 1.6 (95% CI, 1.3-1.9) per decrease of 0.1 g/cm2 in BMD at the spine, femoral neck, and trochanter, respectively. After adjusting for BMD at the spine or trochanter, the gender difference in the predicted age-specific incidence of vertebral fracture was no longer significant (RR = 1.1 and 95% CI, 0.6-1.9 at the spine; RR = 1.5 and 95% CI, 0.8-2.7 at the trochanter), although it persisted after adjusting for femoral neck BMD (RR = 1.9; 95%CI, 1.1-3.3). The presence of a prevalent vertebral deformity was a strong risk factor for future vertebral fracture, although the strength of the association was reduced after adjustment for age, sex, and spine BMD. However, adjustment for the presence of a baseline vertebral deformity did not alter the main findings. In conclusion, at a given age and spine (although not femoral neck) bone density, the risk of incident vertebral fracture is similar in men and women. Incident vertebral fractures are more common in women than men because at any age their spine BMD is lower

Determinants of incident vertebral fracture in men and women: results from the European Prospective Osteoporosis Study (EPOS)

The aim of this analysis was to determine the influence of lifestyle, anthropometric and reproductive factors on the subsequent risk of incident vertebral fracture in men and women aged 50-79 years. Subjects were recruited from population registers from 28 centers across Europe. At baseline, they completed an interviewer-administered questionnaire and had lateral thoraco-lumbar spine radiographs performed. Repeat spinal radiographs were performed a mean of 3.8 years later. Incident vertebral fractures were defined morphometrically and also qualitatively by an experienced radiologist. Poisson regression was used to determine the influence of the baseline risk factor variables on the occurrence of incident vertebral fracture. A total of 3173 men (mean age 63.1 years) and 3402 women (mean age 62.2 years) contributed data to the analysis. In total there were 193 incident morphometric and 224 qualitative fractures. In women, an age at menarche 16 years or older was associated with an increased risk of vertebral fracture (RR=1.80; 95%CI 1.24, 2.63), whilst use of hormonal replacement was protective (RR=0.58; 95%CI 0.34, 0.99). None of the lifestyle factors studied including smoking, alcohol intake, physical activity or milk consumption showed any consistent associations with incident vertebral fracture. In men and women, increasing body weight and body mass index were associated with a reduced risk of vertebral fracture though, apart from body mass index in men, the confidence intervals embraced unity. For most variables the strengths of the associations observed were similar using the qualitative and morphometric approaches to fracture definition. In conclusion our data suggest that modification of other lifestyle risk factors is unlikely to have a major impact on the population occurrence of vertebral fractures. The important biological mechanisms underlying vertebral fracture risk need to be explored using new investigational strategies