title: Incidence of loss of ability to walk 400 meters in a functionally limited older population.
abstract: OBJECTIVE
  To assess the incidence of and factors related to nondisabled but functionally limited older adults aged 75 to 85 years losing the ability to walk 400 m.
  
  
  METHODS
  Observational study with average follow-up of 21 months.
  
  
  METHODS
  Community.
  
  
  METHODS
  At baseline, 101 persons with objective signs of functional limitations and intact cognitive function agreed to participate in the study. Of these, 81 were able to walk 400 m at baseline, and 62 participated in the follow-up examination.
  
  
  METHODS
  Mobility disability was defined as an inability to complete a 400-m walk test. At baseline, eligible participants (n=81) had the ability to walk 400 m, scored between 4 and 9 on the Short Physical Performance Battery (SPPB; range 0-12), and scored 18 or more on the Mini-Mental State Examination. Demographics, difficulty in daily activities, disease status, behavioral risk factors, and muscle strength were assessed at baseline and follow-up.
  
  
  RESULTS
  Of 62 persons at follow-up, 21 (33.9%) developed incident mobility disability. The strongest predictors of loss of mobility were the time to complete the 400-m walk at baseline (odds ratio (OR)=1.6 per 1-minute difference, 95% confidence interval (CI)=1.04-2.45), and decline in SPPB score over the follow-up (OR=1.4 per 1-point difference, 95% CI=1.01-1.92).
  
  
  CONCLUSIONS
  Older persons with functional limitations have a high rate of loss of ability to walk 400 m. The 400-m walk test is a highly relevant, discrete outcome that is an ideal target for testing preventive interventions in vulnerable older populations.
authors.affiliation: Laboratory of Epidemiology, Demography and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA. changmi@hjarta.is <changmi@hjarta.is>
authors.forename: Milan
authors.initials: M
authors.lastname: Chang
authors.forename: Jiska
authors.initials: J
authors.lastname: Cohen-Mansfield
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
authors.forename: Suzanne
authors.initials: S
authors.lastname: Leveille
authors.forename: Stefano
authors.initials: S
authors.lastname: Volpato
authors.forename: Nathalie
authors.initials: N
authors.lastname: de Rekeneire
authors.forename: Jack M
authors.initials: JM
authors.lastname: Guralnik
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D004185:Disability Evaluation; D006233:Persons with Disabilities / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D016330:Frail Elderly / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008396:Maryland; D015999:Multivariate Analysis; D012307:Risk Factors; D016138:Walking