The MBT Adherence and Competence Scale (MBT-ACS): development, structure and reliability

Abstract

The properties of the 17-item Mentalization-Based Treatment Adherence and Competence Scale (MBT-ACS) were investigated in a reliability study in which 18 psychotherapy sessions, comprising two sessions by nine different therapists, were rated by seven different raters. The overall reliabilities for adherence and competence for seven raters were high, .84 and .88 respectively. The level of reliability declined by number of raters but was still acceptable for two raters (.60 and .68). The reliabilities for the various items differed. The MBT-ACS was found to be an appropriate rating measure for treatment fidelity and useful for the purposes of quality control and supervision. The reliability may be enhanced by redefining some items and reducing their numbers.