title: Rasch analyses of the Activities-specific Balance Confidence Scale with individuals 50 years and older with lower-limb amputations.
abstract: OBJECTIVE
  To explore shortened response formats for use with the Activities-specific Balance Confidence (ABC) Scale and then evaluate the unidimensionality of the scale, the item difficulty, the scale for redundancy and content gaps, and the item standard error of measurement (SEM) and internal consistency reliability among aging individuals with a lower-limb amputation living in the community.
  
  
  METHODS
  Secondary analysis of cross-sectional survey and chart review data.
  
  
  METHODS
  Outpatient amputee clinics, Ontario, Canada.
  
  
  METHODS
  Community living adults (N=448; ≥50y; mean, 68y) who have used a prosthesis for at least 6 months for a major unilateral lower-limb amputation. Of the participants, 325 (72.5%) were men.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  ABC Scale.
  
  
  RESULTS
  A 5-option response format outperformed 4- and 6-option formats. Factor analyses confirmed a unidimensional scale. The distance between response options is not the same for all items on the scale, evident by the Rasch Partial Credit Model (PCM) having a better fit to the data than the Rasch Rating Scale Model. Two items, however, did not fit the PCM within statistical reason. Revising the wording of the 2 items may resolve the misfit and improve the construct validity and lower the standard error of measurement. Overall, the difficulty of the scale's items is appropriate for use with aging individuals with lower-limb amputation, and is most reliable (Cronbach α=0.94) for use with individuals with moderately low balance confidence levels.
  
  
  CONCLUSIONS
  The ABC Scale with a simplified 5-option response format is a valid and reliable measure of balance confidence for use with individuals aging with a lower-limb amputation.
authors.affiliation: Graduate Program in Rehabilitation Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Brodie M
authors.initials: BM
authors.lastname: Sakakibara
authors.forename: William C
authors.initials: WC
authors.lastname: Miller
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Backman
mesh_terms: D000368:Aged; D000671:Amputation, Surgical / Q000523:psychology* / Q000534:rehabilitation*; D001186:Artificial Limbs / Q000523:psychology*; D003430:Cross-Sectional Studies; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000601:surgery*; D008297:Male; D009864:Ontario; D004856:Postural Balance / Q000502:physiology*; D011594:Psychometrics; D015203:Reproducibility of Results; D012307:Risk Factors; D020377:Self Efficacy