Characteristics of incidence hip fracture cases in older adults participating in the longitudinal AGES-Reykjavik study.

Abstract

Poor physical function and body composition my partly predict the risk of falls leading to fracture regardless of bone mineral density.

Introduction: To examine the relationship between body composition, physical function, and other markers of health with hip fractures in older community-dwelling Icelandic adults.

Methods: A prospective cohort of 4782 older adults from the AGES-Reykjavik study. Baseline recruitment took place between 2002 and 2006, and information on hip fractures occurring through 2012 was extracted from clinical records. Using multivariate regression analyses, baseline measures of bone health, physical function, and body composition were compared between those who later experienced hip fractures and to those who did not. Associations with the risk of fractures were quantified using Cox regression.

Results: Mean age was 76.3 years at baseline. After adjustment for age, regression showed that male hip fracture cases compared with non-cases had (mean (95% confidence interval)) significantly lower thigh muscle cross-sectional area - 5.6 cm2 (- 10.2, - 1.1), poorer leg strength - 28 N (- 49, - 7), and decreased physical function as measured by longer timed up and go test 1.1 s (0.5, 1.7). After adjustment for age, female cases had, compared with non-cases, lower body mass index - 1.5 kg/m2 (- 2.1, - 0.9), less lean mass - 1.6 kg (- 2.5, - 0.8), thigh muscle cross-sectional area - 4.4 cm2 (- 6.5, - 2.3), and worse leg strength - 16 N (- 25, - 6). These differences largely persisted after further adjustment for bone mineral density (BMD), suggesting that body composition may contribute to the risk of fracture independent of bone health. When examining the association between these same factors and hip fractures using Cox regression, the same conclusions were reached.

Conclusions: After accounting for age and BMD, older adults who later experienced a hip fracture had poorer baseline measures of physical function and/or body composition, which may at least partly contribute to the risk of falls leading to fracture.

Keywords: Aging; Biomarkers; Body composition; Hip fracture; Physical function.