title: The nonlinear relationship between gait speed and falls: the Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly of Boston Study.
abstract: OBJECTIVE
  To examine the relationship between gait speed and falls risk.
  
  
  METHODS
  Longitudinal analysis of the association between gait speed and subsequent falls and analysis of gait speed decline as a predictor of future falls.
  
  
  METHODS
  Population-based cohort study.
  
  
  METHODS
  Seven hundred sixty-three community-dwelling older adults underwent baseline assessments and were followed for falls; 600 completed an 18-month follow-up assessment to determine change in gait speed and were followed for subsequent falls.
  
  
  METHODS
  Gait speed was measured during a 4-m walk, falls data were collected from monthly post-card calendars, and covariates were collected from in-home and clinic visits.
  
  
  RESULTS
  There was a U-shaped relationship between gait speed and falls, with participants with faster (≥1.3 m/s, incident rate ratio (IRR)=2.12, 95% confidence interval (CI)=1.48-3.04) and slower (<0.6 m/s, IRR=1.60, 95% CI=1.06-2.42) gait speeds at higher risk than those with normal gait speeds (1.0-<1.3 m/s). In adjusted analyses, slower gait speeds were associated with greater risk of indoor falls (<0.6 m/s, IRR=2.17, 95% CI=1.33-3.55; 0.6-<1.0 m/s, IRR=1.45, 95% CI=1.08-1.94), and faster gait speed was associated with greater risk of outdoor falls (IRR=2.11, 95% CI=1.40-3.16). A gait speed decline of more than 0.15 m/s per year predicted greater risk of all falls (IRR=1.86, 95% CI=1.15-3.01).
  
  
  CONCLUSIONS
  There is a nonlinear relationship between gait speed and falls, with a greater risk of outdoor falls in fast walkers and a greater risk of indoor falls in slow walkers.
authors.affiliation: From the *Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts; †Division of Gerontology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts; and ‡Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Lien
authors.initials: L
authors.lastname: Quach
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Galica
authors.forename: Richard N
authors.initials: RN
authors.lastname: Jones
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Procter-Gray
authors.forename: Brad
authors.initials: B
authors.lastname: Manor
authors.forename: Marian T
authors.initials: MT
authors.lastname: Hannan
authors.forename: Lewis A
authors.initials: LA
authors.lastname: Lipsitz
mesh_terms: D000054:Acceleration; D000058:Accidental Falls / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D001900:Boston; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D005684:Gait; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D057187:Independent Living; D007360:Intelligence; D008137:Longitudinal Studies; D008297:Male; D009042:Motivation; D017711:Nonlinear Dynamics; D004856:Postural Balance; D012306:Risk