RESUMO
BACKGROUND: There is not a valid Persian tool for measuring the decision-making competency of patients. The aim of this study is to evaluate the face and content validity of the MacArthur Competence Assessment Tool for the treatment of Iranian Persian-speaking patients. METHODS: To assess the validity of the Persian version of the tool, a self-administrated questionnaire was designed. The Lawshe method was also used for assessing each item. Content validity ratio (CVR) and content validity index (CVI) were used to assess the content validity quantitatively. According to the experts' judgment, questions with a CVR ≥0.62 and CVR <0.62 were maintainable and unmaintainable, respectively. RESULTS: The questions were designed in a manner to achieve the desirable result (CVR ≥0.62). The CVI scale (S-CVI) and CVI (S-CVI/Ave) were 0.94 (higher than 0.79). Thus, the content validity was confirmed. CONCLUSIONS: Since capacity assessments are usually based on physician's subjective judgment, they are likely to bias and therefore, with this suitably validated tool, we can improve judgment of physicians and health-care providers in out- and in-patient cases.