Validation of the Drexel University ACT/tCBT adherence and competence rating scale: revised for use in a clinical population

Abstract

This study is a replication and extension of a previous study (McGrath, Forman & Herbert, 2009) that developed and investigated the psychometric properties of the Drexel University ACT/tCBT Adherence and Competence Rating Scale (DUACRS). The DUACRS, a rater-scored measure designed to assess therapist adherence and competence in the delivery of acceptance and commitment therapy (ACT) and traditional cognitive behavioral therapy (tCBT), was designed in order to fill the need for an ACT-specific treatment integrity measure with established psychometric properties and a treatment integrity measure permitting investigation of the specific features of both ACT and tCBT, as well as factors common to both approaches. Recent years have witnessed a growing number of clinical trials investigating ACT, including studies comparing ACT and tCBT. In addition, controversy has surfaced regarding the degree to which the two treatments are truly distinct. A treatment adherence measure is therefore sorely needed to address these issues in future research. Participants were individuals meeting DSM-IV criteria for anxiety disorders who were enrolled in a large clinical trial in which they were randomized to receive either tCBT or ACT. Two recorded therapy sessions were randomly selected for each study participant; these sessions were coded using the DUACRS-R by raters trained in ACT and tCBT in order to investigate its interrater reliability, internal consistency, factor structure, discriminant validity, and overall utility as a treatment adherence measure. Results indicate that the DUACRS-R has good interrater reliability and can be used to successfully distinguish tCBT from ACT. The items on the ACT- and tCBT-Specific behavior and the Competence subscales appear to assess uniform constructs (though the items on the Behavioral and Non-Model-Specific subscales do not). Furthermore, four of the five components extracted through Principal Component Analysis and Principal Axis Factoring corresponded closely to the ACT-Specific Behavior, tCBT-Specific, Behavioral Intervention, and Competence subscales of the DUACRS-R.