The MacArthur Treatment Competence Study. II

This article reports the development and psychometric properties of three standardized and objectively scored measures, the MacArthur Treatment Competence Research Instruments. They were designed to assess abilities related conceptually to four legal standards for competence to consent to treatment: understanding, appreciation, rational manipulation (reasoning), and expressing a choice. Scoring reliability, internal consistency, intertest correlations, and test-retest correlations were examined with data from samples of hospitalized patients with schizophrenia, major depression, and ischemic heart disease, as well as matched non-ill community samples. The results indicate very good interscorer reliability and provide guidance for the use of the instruments and interpretation of their results in future research on patients' decisional abilities in treatment contexts.