title: The reliability, precision and clinically meaningful change of walking assessments in multiple sclerosis.
abstract: BACKGROUND
  Assessing walking impairment in those with multiple sclerosis (MS) is common, however little is known about the reliability, precision and clinically important change of walking outcomes.
  
  
  OBJECTIVE
  The purpose of this study was to determine the reliability, precision and clinically important change of the Timed 25-Foot Walk (T25FW), Six-Minute Walk (6MW), Multiple Sclerosis Walking Scale-12 (MSWS-12) and accelerometry.
  
  
  METHODS
  Data were collected from 82 persons with MS at two time points, six months apart. Analyses were undertaken for the whole sample and stratified based on disability level and usage of walking aids. Intraclass correlation coefficient (ICC) analyses established reliability: standard error of measurement (SEM) and coefficient of variation (CV) determined precision; and minimal detectable change (MDC) defined clinically important change.
  
  
  RESULTS
  All outcome measures were reliable with precision and MDC varying between measures in the whole sample: T25FW: ICC=0.991; SEM=1 s; CV=6.2%; MDC=2.7 s (36%), 6MW: ICC=0.959; SEM=32 m; CV=6.2%; MDC=88 m (20%), MSWS-12: ICC=0.927; SEM=8; CV=27%; MDC=22 (53%), accelerometry counts/day: ICC=0.883; SEM=28450; CV=17%; MDC=78860 (52%), accelerometry steps/day: ICC=0.907; SEM=726; CV=16%; MDC=2011 (45%). Variation in these estimates was seen based on disability level and walking aid.
  
  
  CONCLUSIONS
  The reliability of these outcomes is good and falls within acceptable ranges. Precision and clinically important change estimates provide guidelines for interpreting these outcomes in clinical and research settings.
authors.affiliation: University of Illinois at Urbana-Champaign, USA.
authors.forename: Yvonne C
authors.initials: YC
authors.lastname: Learmonth
authors.forename: Deirdre D
authors.initials: DD
authors.lastname: Dlugonski
authors.forename: Lara A
authors.initials: LA
authors.lastname: Pilutti
authors.forename: Brian M
authors.initials: BM
authors.lastname: Sandroff
authors.forename: Robert W
authors.initials: RW
authors.lastname: Motl
mesh_terms: D061725:Accelerometry; D000328:Adult; D002183:Canes; D003446:Crutches; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D009103:Multiple Sclerosis / Q000175:diagnosis / Q000503:physiopathology*; D009460:Neurologic Examination / Q000592:standards*; D015203:Reproducibility of Results; D016896:Treatment Outcome; D016138:Walking
keywords: EDSS; Multiple sclerosis; clinical change; mobility; outcome measures; precision; reliability; walking