Development and Psychometric Assessment of "Self-Efficacy Scale" for Patients With Beta Thalassemia Major: A Mixed-Methods Study.

Background and Purpose: Since self-efficacy is a significant factor influencing the self-management of chronic diseases, including thalassemia major, it is considered a key concept in chronic diseases. This study aimed to develop and psychometrically evaluate the self-efficacy scale for patients with thalassemia major. Methods: This was a mixed-methods study conducted in two phases. In phase 1, a qualitative study with a conventional content analysis design was conducted. In phase 2, which was a quantitative one, the psychometric analysis of the instrument's phrases was done. Results: The instrument has 35 items and 3 factors. The Cronbach's alpha coefficient and the intraclass correlation coefficient were .93 and .94, respectively. Conclusions: This study confirms the validity and reliability of the Beta Thalassemia Major Self-Efficacy Scale. With this tool, nurses can evaluate the self-efficacy of patients with thalassemia major.