Cross-Cultural Adaptation and Measurement Properties of the Expectations for Treatment Scale (ETS) for Greek-Speaking Patients.

Abstract

Introduction Patients' treatment expectations are key factors influencing the health outcomes in various medical conditions. Using validated measures to capture these expectations has been strongly suggested to improve the prognosis of the health outcome and promote research investigations. The Expectations for Treatment Scale (ETS) is a well-established questionnaire designed to accurately measure treatment expectations in patients with low back pain; however, it is not available in Greek yet. We aimed to translate and cross-culturally adapt the ETS in Greek (ETS-Gr) and evaluate its reliability and validity in a Greek-speaking population with musculoskeletal disorders. Methods We followed published recommendations for the translation and cross-cultural adaptation process of the scale.Face and content validity were evaluated using interviews with patients and experts. Internal consistency, test-retest reliability, and measurement error were evaluated in 52 patients with musculoskeletal conditions. Results During forward and backward translation minor linguistic discrepancies were detected and effectively adapted for Greek-speaking patients. The ETS-Gr presented a high level of content validity (item content validity index: 0.88-1; and average scale content validity index: 0.90), acceptable internal consistency (Cronbach's alpha: 0.84), and excellent test-retest reliability (intraclass correlation coefficient: 0.96, 95% confidence interval: 0.93-0.98). Conclusions The ETS-Gr is a short, reliable, and valid instrument to measure pre-treatment expectations in patients with musculoskeletal disorders. Future investigations including other medical conditions are required.