Factor analysis of the Achievement of Therapeutic Objectives Scale (ATOS) in short-term dynamic psychotherapy and cognitive therapy

This study examined the factor structure of the Achievement of Therapeutic Objectives Scale (ATOS; McCullough, Larsen, et al., 2003) in short-term dynamic psychotherapy (STDP) and cognitive therapy (CT). The ATOS is a process scale that has shown promise as a measure of patients' achievements of treatment objectives in STDP and CT and is conceptualized as comprising 7 subscales hypothesized to cluster according to 3 main treatment objectives (defense restructuring, affect restructuring, and restructuring of sense of self and others). However, the factor structure of the ATOS has not been examined empirically previously. Data were derived from ratings of videotaped therapy sessions from a randomized controlled trial, comparing STDP and CT for patients with Cluster C personality disorders. The model fit of a 2- and 3-factor solution was examined in the combined patient sample, as well as in each treatment separately, utilizing structural equation modeling. Both a 2- and 3-factor model provided acceptable fit to the data. The results add to the psychometric soundness of the ATOS as an innovative observer-based instrument for examining process in STDP and CT.