Obesity, bone density relative to body weight and prevalent vertebral fracture at age 62 years: the Newcastle thousand families study

A Summary Obesity increases the likelihood of prevalent vertebral fracture (VF) in men and women at age 62 years. The higher absolute bone mineral density (BMD) observed in obese individuals is disproportionate to body weight, and this may partly explain the greater prevalence of VF in this group. Introduction Obesity is a global epidemic, and there remains uncertainty over the effect of obesity on skeletal health, particularly in the context of osteoporosis. The aim of this study was to investigate associations of body mass index (BMI) and obesity with BMD and prevalent VF in men and women aged 62 years. Methods Three hundred and forty-two men and women aged 62.5 +/- 0.5 years from the Newcastle Thousand Families Study birth cohort underwent DXA evaluations of femoral neck and lumbar spine BMD and of the lateral spine for vertebral fracture assessment. Results The likelihood of prevalent VF was significantly increased in men when compared to women (OR = 2.7, p < 0.001, 95% Cl 1.7-4.4). As BMI increased in women, so did the likelihood of prevalent any-grade VF (OR = 1.09, p = 0.006, 95% CI 1.02-1.17). Compared to normal weight women, obese women were more likely to have at least one VF (OR = 2.65, p = 0.025, CI 1.13-6.20) and at least one grade 1 vertebral deformity (OR = 4.39, p = 0.005, CI 1.57-12.28). Obese men were more likely to have a grade 2 and/or grade 3 VF compared to men of normal weight (OR = 3.36, p = 0.032, CI 1.11-10.16). In men and women, BMI was negatively associated with femoral neck BMD/weight (R = -0.65, R = -0.66, p < 0.001) and lumbar spine BMD/weight (R = -0.66, R-0.60, p < 0.001). Conclusions Obesity appears to be a risk factor for prevalent VF, and although absolute BMD is higher in obese individuals, this does not appear commensurate to their increased body weight.