title: Construct Validity of the Four Square Step Test in Multiple Sclerosis.
abstract: To expand the construct validity of the Four Square Step Test (FSST) in people with multiple sclerosis (PWMS).
  
  
  
  Cross-sectional study.
  
  
  
  Multiple sclerosis center.
  
  
  
  PWMS (N=218; 133 women, 85 men; mean age, 43.2±13.5y; mean disease duration, 7.5±7.7y since diagnosis) were enrolled in the study. The Expanded Disability Status Scale score was 3.1±1.3, indicating minimal to moderate neurologic disability.
  
  
  
  Not applicable.
  
  
  
  The FSST, posturography measures, 2-minute walk test, timed Up & Go test, timed 25-foot walk, fall status, Falls Efficacy Scale International, Modified Fatigue Impact Scale, instrumented cognitive assessment, and 12-item Multiple Sclerosis Walking Scale.
  
  
  
  The FSST score of the total sample was 11.0±4.9. Significant differences were observed between the very mild, mild, and moderate disability groups: 8.8±3.4, 11.1±4.9, and 14.1±5.3, respectively. In terms of fall status, the fallers demonstrated a significant slower FSST score than the nonfallers (12.5±5.7 vs 9.0±2.6, respectively). Modest significant correlation scores were found between the FSST and the timed Up & Go test and 2-minute walk test (Pearson ρ=.652 and ρ=-.575, respectively). In terms of posturography, all measures were significantly associated with the FSST scores. A significant positive relation was observed with the visual spatial cognitive domain (Pearson ρ=-.207).
  
  
  
  The current study supports and broadens the construct validity of the FSST in PWMS.
authors.affiliation: Department of Physical Therapy, School of Health Professions, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel. Electronic address: alkalron@gmail.com.
authors.forename: Alon
authors.initials: A
authors.lastname: Kalron
authors.affiliation: Multiple Sclerosis Center, Sheba Medical Center, Tel Hashomer, Ramat-Gan, Israel; Department of Pediatric Orthopedics, Sheba Medical Center, Tel Hashomer, Tel-Aviv, Israel; Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Givon
mesh_terms: D000058:Accidental Falls / Q000706:statistics & numerical data; D000328:Adult; D003071:Cognition; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000534:rehabilitation*; D026741:Physical Therapy Modalities / Q000592:standards*; D004856:Postural Balance / Q000502:physiology; D015203:Reproducibility of Results; D012307:Risk Factors; D012720:Severity of Illness Index; D016138:Walking / Q000502:physiology
keywords: Accidental falls; Gait; Multiple sclerosis; Postural balance; Rehabilitation; Walking