Objective: To investigate the cross-cultural validity of the Orthotics and Prosthetics Users’ Survey (OPUS), to investigate differential item functioning (DIF) in the OPUS related to sex, age, amputation level and amputated sides (unilateral or bilateral), and to determine the known-group validity of the OPUS.
Design: Cross-sectional study design.
Setting: 2 outpatient clinics in Sweden and 7 outpatient clinics in the United States.
Participants: A total of 195 Swedish and 126 American adults using lower limb prosthesis.
Interventions: Not applicable.
Main Outcome Measure: 4 modules from the OPUS were used in this study, including the Lower extremity functional status (LEFS), Client satisfaction with device (CSD), Client satisfaction with services (CSS), and Health-related quality of life (HRQoL) modules. Items were scored on 4- or 5-level Likert scales, and a Rasch measure was calculated for each person and module.
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 the CSD and CSS needed adjustments, and the unidimensionality of the CSD and CSS was weak. The differences between the mean measures of known patient groups were statistically significant for age in the LEFS and for the level of amputation in the CSD.
Conclusions: This study supports the validity of comparing OPUS measures between Sweden and USA and between patient groups with different demographic characteristics. The OPUS can, to some extent, discriminate between patient groups known to be different. The unidimensionality of the CSD and CSS modules is weaker than the other modules and these need further development and evaluation.
rehabilitation, artificial limbs, outcome assessment (health care), validation studies, cross-cultural comparison
Detta manuskript har bearbetats till en artikel som är under publicering i tidskriften Archives of Physical Medicine and Rehabilitation