Associations of Body Composition Trajectories with Bone Mineral Density, Muscle Function, Falls, and Fractures in Older Men: The Concord Health and Ageing in Men Project

Background: Weight loss increases fracture risk in older adults. We aimed to determine associations of 2-year body composition trajectories with subsequent falls and fractures in older men. Methods: We measured appendicular lean mass (ALM) and total fat mass (FM) by dual-energy X-ray absorptiometry at baseline and Year 2 in 1,326 community-dwelling men aged >= 70 and older. Body composition trajectories were determined from residuals of a linear regression of change in ALM on change in FM (higher values indicate maintenance of ALM over FM), and a categorical variable for change in ALM and FM (did not lose [>=-5% change] versus lost [<-5% change]). Bone mineral density (BMD), hand grip strength, and gait speed were assessed at Years 2 and 5. After Year 2, incident fractures (confirmed by radiographical reports) and falls were recorded for 6.8 years. Results: Compared with men who did not lose ALM or FM, men who did not lose ALM but lost FM, and men who lost both ALM and FM, had reduced falls (-24% and -34%, respectively; both p < .05). Men who lost ALM but did not lose FM had increased falls (incidence rate ratio = 1.73; 95% CI 1.37-2.18). ALM/FM change residuals were associated with improved lumbar spine BMD (B = 0.007; 95% CI 0.002-0.012 g/cm(2) per SD increase) and gait speed (0.015; 0.001-0.029 m/s), and reduced hip fractures (hazard ratio = 0.68; 95% CI 0.47-0.99). Conclusions: Fracture risk may be increased in older men who lose higher ALM relative to FM. Weight loss interventions for obese older men should target maintenance of lean mass.