The German Version of the Satisfaction with Prosthesis Questionnaire: Translation, Adaptation, Reliability, and Validity in Adults with Major Lower-Limb Amputation

Abstract

Introduction:The aim of this study was to translate and cross-culturally adapt the Satisfaction with Prosthesis Questionnaire (SAT-PRO) into German and to evaluate its validity and reliability. Materials and Methods: The 2-fold forward and backward translations were carried out according to the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines. Subsequently, the German version of the SAT-PRO was administered to 68 patients with major lower-limb amputation (LLA) fitted with a prosthesis. The internal consistency, floor and ceiling effects, item-to-total correlation, and test-retest reliability were determined. In addition, the standard error of the mean (SEM) and minimal detectable change (MDC) were calculated. Convergent construct validity was assessed by correlation to a Numerical Rating Scale for Satisfaction Level (NRS-SAT), the 36-Item Short-Form Health Survey (SF-36), the Rivermead Mobility Index (RMI), and the Medicare Functional Classification Level (K-Levels). Descriptive subgroup analysis included levels of amputation (transtibial vs. transfemoral persons with amputations) and user type (long-term vs. subacute users). Results: The mean SAT-PRO total score was 32.27 ± 6.89 (77.6%). Internal consistency was high (Cronbach α = 0.88), and reproducibility demonstrated excellent findings with an intraclass correlation coefficient (ICC 2,1 ) of 0.90 (95% confidence interval [CI], 0.84-0.94). Floor or ceiling effects were not detected. Convergent construct validity indicated a strong correlation to the NRS-SAT (r = 0.89), K-Levels (r = 0.66), and RMI (r = 0.52, all with P < 0.001). Moderate to high correlations were shown to all eight domains of the SF-36 (in a range of r = 0.55 [physical function] to r = 0.39 [mental health], all with P < 0.001). MDC was 2.32 (MDC% = 3.4%). Conclusions: The translation according to ISPOR guidelines and cross-cultural adaptation of the SAT-PRO into German were successfully conducted in the pilot study. The psychometric testing showed high reliability and validity of the German version of the SAT-PRO. Hence, it can be used as an outcome measure to assess a patient's satisfaction with prosthesis in a Germanspeaking population. Clinical Relevance Statement: The SAT-PRO can make an important contribution to the treatment of patients with major LLA. The use of objective measurement parameters and guideline-based translation should be applied to increase the validity and comparability of the data.