Abstract

Background: The theory if self-efficacy is the central concept of social cognitive theory with emphasis on the constructs of efficacy expectation, outcome expectation. Efficacy expectation is defined as the person’s confidence to carry out a specific behavior. Outcome expectation is beliefs that carrying out a specific behavior will lead to a specific outcome. While the benefit of measuring outcome expectations has been established, there has been no large scale within the Iranian context. The purpose of this study is to examine the reliability-validity of the Persian version of the Perceived Therapeutic Efficacy Scale (PTES). Methods: This study was conducted among 160 patients with type 2 diabetes mellitus (T2DM) using a self-administered instrument measuring outcome expectation. We used a methodological study design to assess the validity and reliability of the translated Persian version of the instrument. Results: The findings of the present study support the uni-dimensionality of the Persian version of the instrument. The 10 items of the scale account for 73.54 of the total variance and the un-rotated factor loadings ranged from 0.66 to 0.93. Moreover, this study offers support for convergent validity and internal consistency of the scale. Conclusion: Our study demonstrated good convergent validity, factor structure and internal consistency in a sample of 160 Iranian adults with T2DM. Therefore, the Persian version of the scale is a valid and reliable instrument and can be used in research and clinical settings. © 2018 The Author(s).