title: Trajectories of Lower Extremity Physical Performance: Effects on Fractures and Mortality in Older Women.
abstract: Prior studies have only considered one measurement of physical performance in its relationship to fractures and mortality. A single measurement is susceptible to large within-person changes over time, and thus, may not capture the true association between physical performance and the outcomes of interest.
  
  
  
  Using data from the Study of Osteoporotic Fractures, we followed 7,015 women enrolled prior to age 80 years who had outcome information beyond this age. Trajectories of walking speed (m/s) and chair stand speed (stands/s) were estimated up to the last visit prior to age 80 years using mixed-effects linear regression. Physical performance at age 80 (PF_age80) was assessed at the last visit prior to age 80 years. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression and multivariate models adjusted for all other covariates.
  
  
  
  Greatest walking speed decline and chair stand speed decline were both associated with higher risk of hip fracture (HR: 1.28; 95% CI: 1.03, 1.58 and HR: 1.26; 95% CI: 1.03, 1.54, respectively), but not nonspine fractures. Greatest walking speed decline and chair stand speed decline were both associated with a significant 29% (95% CI: 17-42%) and 27% (95% CI: 15-39%) increased risk of mortality, respectively.
  
  
  
  Greatest declines in walking speed and chair stand speed were both associated with an increased risk of hip fracture and mortality independent of PF_age80 and other important confounders. Both physical performance change and the single physical performance measurement should be considered in the etiology of hip fracture and mortality.
authors.affiliation: Department of Epidemiology, University of Pittsburgh, Pennsylvania. iyk1@cdc.gov.
authors.forename: Kamil E
authors.initials: KE
authors.lastname: Barbour
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco.
authors.forename: Li-Yung
authors.initials: LY
authors.lastname: Lui
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Charles E
authors.initials: CE
authors.lastname: McCulloch
authors.affiliation: University of Minnesota and Minneapolis VAHS.
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco.
authors.forename: Peggy M
authors.initials: PM
authors.lastname: Cawthon
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco.
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Barnes
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Massachusetts.
authors.forename: Lisa
authors.initials: L
authors.lastname: Fredman
authors.affiliation: Department of Epidemiology, University of Pittsburgh, Pennsylvania.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.affiliation: California Pacific Medical Center Research Institute, San Francisco.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Cummings
authors.affiliation: Department of Epidemiology, University of Pittsburgh, Pennsylvania.
authors.forename: Jane A
authors.initials: JA
authors.lastname: Cauley
mesh_terms: D000368:Aged; D015986:Confounding Factors, Epidemiologic; D005260:Female; D015577:Geriatric Assessment; D006620:Hip Fractures / Q000453:epidemiology*; D006801:Humans; D035002:Lower Extremity / Q000503:physiopathology*; D051346:Mobility Limitation; D009026:Mortality / Q000639:trends*; D011446:Prospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D000072797:Walking Speed
keywords: Fractures; Mortality; Physical performance; Trajectories