Bone Abstracts

Low body mass index (BMI) or body weight is a well-known risk factor for osteoporosis and fragility fractures. However, the relative contribution of lean mass and fat mass on bone health, i.e. fragility fractures is inconclusive.

We elucidated the relative contribution of lean and fat mass on fracture risk by group analysis in Korean men and women. This was an ongoing prospective community-dwelling cohort study at Ansung in Korea, begun in 2001. We included 2189 men and 2625 women aged over 40 years. Lean and fat mass was measured using bioelectrical impedance analysis. Study subjects were classified into four groups; non-sarcopenic and non-obese, sarcopenic, obese, sarcopenic obese group according to the gender-specific criteria. Clinical fracture events were assessed at baseline and biennially using a self-reported questionnaires.

During a median follow-up duration of 9.4 years, 77 (3.6%) men and 203 (8.4%) women experienced at least one incident fracture. In cox proportional hazard models for fragility fractures, sarcopenic men had a higher risk for fragility fractures than normal ones even after adjusted for age, height, physical activity, speed of sound at radius, regular exercise, a history of smoking, a history of drinking, chronic diseases, family history of fracture, and previous history of fracture (hazard ratio (HR)=2.45, 95% CI=1.29–4.63), Obese (HR=0.41, 95% CI=0.16–1.04) or sarcopenic obese men (HR=0.2.47, 95% CI=0.32–18.9) did not have increased risk for fragility fractures compared with normal ones. On the other hand, only sarcopenic obese women had a higher risk for fragility fracture than normal ones after adjustment for covariates (HR=6.75, 95% CI=2.68–17.0). Sarcopenic (HR=1.11, 95% CI=0.71–1.72) or obese (HR=1.23, 95% CI=0.82–1.85) women were not at higher risk for fractures than normal group.

We demonstrated the gender-different association between body composition and fracture risk in Koreans aged over 40 years for 10 years. Strengthening muscle mass in men and simultaneous reducing excess fat mass in women is vital in keeping bone health and preventing fragility fractures in Koreans.