Cross-cultural adaptation and validation of the Turkish version of the arthritis self-efficacy scale-8 (ASES-8) in patients with knee osteoarthritis

Abstract

Self-efficacy plays a key role in managing chronic conditions such as knee osteoarthritis (KOA), and reliable tools are needed to assess it in different languages and cultures. The arthritis self-efficacy scale-8 (ASES-8) is a widely used measure, but a validated Turkish version is not yet available. This study aimed to develop a Turkish version of the ASES-8 and evaluate its validity and reliability. The ASES-8 questionnaire was translated into Turkish following a standardized cross-cultural adaptation process. Initially, the clarity and comprehensibility of the Turkish version were tested in a sample of 10 patients with knee osteoarthritis (KOA). Subsequently, the final version was administered to an additional 80 KOA patients. All participants completed the questionnaire again 7 days later to assess test–retest reliability. Floor or ceiling effects were considered present if more than 15% of participants obtained the lowest (1) or highest (10) possible score on the scale. Construct validity was assessed in accordance with COSMIN guidelines by testing predefined a priori hypotheses regarding correlations between the ASES-8 and related measures, and structural validity through confirmatory factor analysis, testing a 1-factor (unidimensional) model. Reliability was evaluated through internal consistency (Cronbach’s α), test–retest reliability (intraclass correlation coefficient), and measurement error (SEMagreement and individual-level smallest detectable change). Confirmatory factor analysis supported the 1-factor structure, showing excellent fit indices (using the relative chi-square index, the goodness-of-fit index, the Tucker–Lewis index, and the normed fit index). The internal consistency was excellent, with a Cronbach’s α of 0.968. The test–retest reliability demonstrated strong stability for both the total scores and the individual items. Hypothesis testing for construct validity was established through strong positive correlations with the pain self-efficacy questionnaire and strong negative correlations with the Tampascale of kinesiophobia; the pain catastrophizing scale; the Western Ontario and McMaster Universities Osteoarthritis Index; and the depression, anxiety, and stress subscales of the depression anxiety and stress scale-42 (r = −0.80 to 0.91). No ceiling effect and minimal floor effect were observed at the total score level. The Turkish version of the ASES-8 has demonstrated evidence of validity and reliability for assessing self-efficacy in patients with knee osteoarthritis.