title: Meaningful change in measures of gait variability in older adults.
abstract: OBJECTIVE
  Gait variability is an important indicator of impaired mobility in older adults; however, little is known about the meaning of change in gait variability over time. This study estimated clinically meaningful change in measures of gait variability using both distribution- and anchor-based approaches.
  
  
  METHODS
  Community-based observational cohort study.
  
  
  METHODS
  Bronx County and the research center at Albert Einstein College of Medicine.
  
  
  METHODS
  Of 1148 participants in the Einstein Aging Study, 241 had quantitative gait assessments in two consecutive years between 2001 and 2005.
  
  
  METHODS
  Gait variables were collected using a 12-foot instrumented walkway as participants walked at their normal walking speed. Gait variability was defined as the within-person standard deviation (SD) across steps in two 12-foot walks. Distribution-based meaningful change estimates used Cohen's effect size (0.2 for small and 0.5 for moderate effects). Anchor-based estimates were obtained using dichotomous and ordinal self-reported walking ability ratings as anchors.
  
  
  RESULTS
  Distribution-based estimates for small and substantial changes of variability measures were: stance time 0.005 and 0.014 s; swing time 0.003 and 0.009 s; step length 0.24 and 0.61 cm; and step width 0.03 and 0.08 cm. Among those reporting no change in walking ability, measures of gait variability were stable over 1 year. Among those reporting a decline in walking, stance time and swing time variability increased. Among those reporting an improvement in walking, only step length variability improved.
  
  
  CONCLUSIONS
  Preliminary criteria for meaningful change are 0.01 s for stance time and swing time variability and 0.25 cm for step length variability. These estimates may identify important changes over time in both clinical settings and research studies.
authors.affiliation: Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA, USA. jbrach@pitt.edu
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brach
authors.forename: Subashan
authors.initials: S
authors.lastname: Perera
authors.forename: Stephanie
authors.initials: S
authors.lastname: Studenski
authors.forename: Mindy
authors.initials: M
authors.lastname: Katz
authors.forename: Charles
authors.initials: C
authors.lastname: Hall
authors.forename: Joe
authors.initials: J
authors.lastname: Verghese
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D005684:Gait / Q000502:physiology*; D015577:Geriatric Assessment; D006304:Health Status; D006801:Humans; D008297:Male; D051346:Mobility Limitation