General medication adherence scale in patients with chronic illnesses: Persian translation and psychometric evaluation

Abstract

Objectives This study was conducted with the aim of determining the validity and reliability of the Persian version of “General Medication Adherence Scale (GMAS)” in chronic patients in Iran. Methodology The study was conducted among patients with chronic diseases in five hospitals of Iran. In this study, after cultural validation, using the steps of Content, Response Reaction, and Internal structure evaluations, the research sample was increased to 150 individuals for exploratory factor analysis (EFA) and 313 chronic patients for confirmatory factor analysis (CFA) to confirm the construct validity. Cronbach's alpha coefficient was used to assess internal consistency, and test-retest method was used to evaluate the reliability of the tool. Findings The results of EFA and CFA confirmed the tool with three factors and 11 items. The R2 index in the above model was estimated at 0.99, indicating that 99% of the variation in medication adherence scores in research units was explained by GMAS with 11 items. The main indices of the model in factor analysis were all above 0.9, indicating a good fit for the model. Discussion Overall, the study results showed that the Persian version of GMAS has acceptable and practical characteristics for evaluating medication adherence, and it can be used as a valid tool in various related fields.