title: Decline in Fast Gait Speed as a Predictor of Disability in Older Adults.
abstract: OBJECTIVE
  To determine whether fast gait speed at study baseline and change in gait speed had independent associations with disability onset.
  
  
  METHODS
  Cohort study with 11-year follow-up (1999-2010).
  
  
  METHODS
  Three-City Study center, Dijon, France.
  
  
  METHODS
  Community-dwelling individuals aged 65 to 85 (N = 3,814, 61% female).
  
  
  METHODS
  Fast gait speed (over 6 m) was assessed up to five times and disability (mobility (Rosow-Breslau scale), instrumental activities of daily living (IADLs; Lawton-Brody scale), basic activities of daily living (ADLs; Katz scale)) six times. A hierarchical disability indicator was constructed; participants were considered disabled if they reported difficulties with mobility and IADLs or with mobility, IADLs, and ADLs. The association between baseline fast gait speed and its slope of change and disability incidence was examined using joint models for longitudinal and time-to-event data.
  
  
  RESULTS
  Over follow-up, 628 participants (68% women) developed disability. Mean fast gait speed at baseline was 1.54 m/s, and annual decline was 0.017 m/s. The hazard ratio of disability per standard deviation (SD) (-0.22 m/s) slower baseline fast gait speed was 1.77 (95% confidence interval (CI) = 1.60-1.94) and for one-SD (-0.013 m/s) faster annual decline was 1.38 (95% CI = 1.10-1.73) when both parameters were included in a sex- and age-adjusted model. All associations remained statistically significant in multivariable models, except for slope of change when chronic conditions were added to the model; of chronic conditions, dyspnea was the main contributor.
  
  
  CONCLUSIONS
  Accelerated decline in fast gait speed was associated with disability independent of baseline fast gait speed. These results confirm the importance of measuring gait speed repeatedly in elderly adults to identify those at higher risk of disability and the need to identify determinants of decline, because they are likely to be targets for prevention and treatment to reduce disability risk.
authors.affiliation: INSERM, Centre for Research in Epidemiology and Population Health, U1018, Epidemiology of Ageing and Age-Related Diseases, Villejuif, France.|UMRS 1018, University Versailles St-Quentin, Versailles, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Artaud
authors.affiliation: INSERM, Centre for Research in Epidemiology and Population Health, U1018, Epidemiology of Ageing and Age-Related Diseases, Villejuif, France.|UMRS 1018, University Versailles St-Quentin, Versailles, France.|Department of Epidemiology and Public Health, University College London, London, UK.
authors.forename: Archana
authors.initials: A
authors.lastname: Singh-Manoux
authors.affiliation: INSERM, Centre for Research in Epidemiology and Population Health, U1018, Epidemiology of Ageing and Age-Related Diseases, Villejuif, France.|UMRS 1018, University Versailles St-Quentin, Versailles, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Dugravot
authors.affiliation: INSERM U897, Neuroepidemiology Team, Bordeaux, France.|University of Bordeaux, Bordeaux, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Tzourio
authors.affiliation: INSERM, Centre for Research in Epidemiology and Population Health, U1018, Epidemiology of Ageing and Age-Related Diseases, Villejuif, France.|UMRS 1018, University Versailles St-Quentin, Versailles, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Elbaz
mesh_terms: D000054:Acceleration; D000058:Accidental Falls / Q000517:prevention & control; D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D016001:Confidence Intervals; D004185:Disability Evaluation; D006233:Persons with Disabilities; D005260:Female; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D016017:Odds Ratio; D004856:Postural Balance / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology*
keywords: aged; cohort study; disability; epidemiology; motor decline