Cross-cultural adaptation and Rasch validation of the Slovene version of the Orthotics and Prosthetics Users' Survey (OPUS) Client Satisfaction with Device (CSD) in upper-limb prosthesis users.

Abstract

To validate the Slovene version of the Orthotics and Prosthetics Users' Survey (OPUS) 8-item Client Satisfaction with Device (CSD) questionnaire in upper-limb prosthesis users and to further verify measurement properties of this tool with Rasch analysis. Participants consisted of a convenience sample of 76 adults (54 men) using a prosthesis after unilateral upper-limb amputation who consecutively attended a follow-up visit at our centre. After translation and cross-cultural adaptation of the CSD into the Slovene language, we evaluated functioning of the rating scale categories, item fit (internal construct validity), reliability indices and dimensionality, as well as convergent and discriminant construct validity of the questionnaire. Rasch analysis indicated that: (1) functioning of the 4 response options was acceptable; (2) all items fitted the measured construct [information-weighted (infit) and outlier-sensitive (outfit) mean-square statistics 0.60 to 1.40]; (3) person separation reliability was 0.62 (and Cronbach α=0.76), item separation reliability was 0.83; (4) on principal component analysis (PCA) on the standardised residuals, the CSD showed borderline but acceptable unidimensionality and no local item dependency. Moreover, as expected, the CSD score showed good correlation with the QUEST 2.0 score (rs=0.57) and little to fair correlation with the OPUS Upper Extremity Functional Status score (rs=0.21). The metric properties of the Slovene version of CSD agree with previous studies. The present study confirms the validity of CSD for measuring patient satisfaction with an upper-limb device, enhances the confidence in this tool for assessing upper-limb prosthesis users, and contributes to further refining the technical quality of this measure.