title: Cross-Cultural Validity and Differential Item Functioning of the Orthotics and Prosthetics Users' Survey With Swedish and United States Users of Lower-Limb Prosthesis.
abstract: OBJECTIVE
  To investigate the cross-cultural validity of the Orthotics and Prosthetics Users' Survey (OPUS), to evaluate differential item functioning (DIF) related to country, sex, age, amputation level, and amputated side (unilateral, bilateral), and to determine known-group validity of the OPUS.
  
  
  METHODS
  Survey.
  
  
  METHODS
  Outpatient clinics.
  
  
  METHODS
  The sample (N=321) consisted of Swedish (n=195) and U.S. (n=126) adults using lower-limb prostheses.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Four OPUS modules were used: lower extremity functional status, client satisfaction with device (CSD), client satisfaction with services (CSS), and health-related quality of life. Rasch analysis was used to calculate measures for persons and items.
  
  
  RESULTS
  The cross-cultural validity was satisfactory. Many items demonstrated DIF related to country and demographic characteristics, but the impact on mean person measures was negligible. The rating scales of CSD and CSS needed adjustments, and the unidimensionality of CSD and CSS was weak. The differences between the mean measures of known patient groups were statistically significant for 2 out of 6 comparisons.
  
  
  CONCLUSIONS
  This study supports the validity of OPUS measure comparisons between Sweden and the United States and between subgroups with different demographic characteristics. Some of the country-related DIF may reflect the different health care financing systems. The findings demonstrate that the OPUS can discriminate between certain patient groups. The results also challenge some of our preconceptions about persons with bilateral amputation, indicating that we might know these persons less well than we think.
authors: Department of Prosthetics and Orthotics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; School of Health and Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden. Electronic address: gustav.jarl@regionorebrolan.se.
authors: Gustav
authors: G
authors: Jarl
authors: Rehabilitation Institute of Chicago, Chicago, IL; Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors: Allen W
authors: AW
authors: Heinemann
authors: School of Health and Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors: Helen Y
authors: HY
authors: Lindner
authors: Department of Prosthetics and Orthotics, Faculty of Medicine and Health, Örebro University, Örebro, Sweden; School of Health and Medical Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors: Liselotte M
authors: LM
authors: Norling Hermansson
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000671:Amputation, Surgical / Q000534:rehabilitation*; D001186:Artificial Limbs; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires / Q000592:standards*; D013548:Sweden; D014481:United States
keywords: Artificial limbs; Cross-cultural comparison; Outcome assessment (health care); Rehabilitation; Validation studies as topic