Accelerated decline in quadriceps area and Timed Up and Go test performance are associated with hip fracture risk in older adults with impaired kidney function

Objective: This study aimed to examine whether an accelerated decline in quadriceps cross-sectional area (CSA), attenuation (a surrogate of quality), and strength, as well as lower limb muscular function, are associated with hip fractures in older adults with impaired kidney function. Design: Prospective population-based study. Setting: Community-dwelling old population in Reykjavik, Iceland. Subjects: A total of 875 older adults (mean baseline age 76 years) from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study with impaired kidney function. Methods: Quadriceps CSA and density were determined using computed tomography (CT), knee extension strength was measured with an isometric dynamometer chair, and muscular function was assessed using the Timed Up and Go (TUG) test. All muscle-related measurements were assessed twice over a mean follow-up of 5.2 years. Data on hip fracture incidence was obtained from medical records during a maximum of 8.4 years of follow-up time. Results: Fully adjusted cox-proportional hazard regression models showed that a faster decline in quadriceps CSA and TUG test performance were significantly associated with increased hip fracture risk (HR = 1.55, 95% CI = 1.02?2.36, and HR = 1.80, 95% CI = 1.19?2.72, respectively). A faster decrease in quadriceps density and isometric knee extension strength were not associated with fracture risk. Conclusions: Accelerated decline in CT-derived quadriceps CSA and muscular function, as measured by the TUG test?s performance, are predictive of hip fracture risk in older adults with impaired kidney function. TUG test is a simple measure and easily included in routine medical examinations, compared to CT scans, which seems to be useful for identifying a subgroup of individuals with high risk of fracture.