Translation, Test-retest Reliability and Construct Validity of the German Version of the Exercise Self-Efficacy Scale in People with Axial Spondyloarthritis

Background Physical activity can improve disease-related symptoms in people with axSpA. In this context, self-efficacy for physical activity is an important predictive factor. The "Exercise Self-Efficacy Scale" (ESES) questionnaire can be used to assess self-efficacy for physical activity. However, a transculturally adapted German version of the questionnaire does currently not exist. Objective To examine the transculturally adapted German version of the ESES (ESES-D) regarding its test-retest reliability, internal consistency, and construct validity in people with axSpA. Method The TRAPD Team Translation Model was used to translate the questionnaire in German. The ESES-D was subsequently evaluated in an observational study. The internal consistency was assessed using Cronbach's alpha and the test-retest reliability using the intraclass-coefficient (ICC, Two-way mixed effects model). Construct validity was examined based on a priori defined hypotheses using correlations between the ESES-D, demographic characteristics and measurement instruments on disease-related symptoms, functional limitations, physical activity, and outcome expectancy for training. The validity was considered valid if 6 out of 8 hypotheses were confirmed. Results The questionnaire was translated into German. 52 subjects between 31 and 80 years were included. The German version of the ESES indicated good values of reliability with an ICC of 0.78 (95 % CI; 0.63-0.88), and an alpha-coefficient of 0.85. 5 out of 8 a priori defined hypotheses were confirmed, thus, validity was not confirmed. Conclusion The ESES-D measures self-efficacy for physical activity with good test-retest reliability and internal consistency. Construct validity could not be terminatory confirmed. Further research on construct validity and responsiveness is recommended.