Psychometric Properties of the Norwegian Version of the Cognitive Therapy Adherence and Competence Scale (CTACS) and Its Associations With Outcomes Following Treatment in IAPT Norway

Abstract

Background:No studies have examined the underlying structure or predictive validityof the Cognitive Therapy Adherence and Competence Scale (CTACS). Examining thestructure of the CTACS is of great relevance because it couldprovide information onwhat constitutes competence in CBT, and whether some underlying factors are moreimportant for predicting treatment outcomes than others. This study investigates thepsychometric properties of the Norwegian version of CTACS and its associations withtreatment outcomes in a sample of primary care clients who received CBT for anxietyand/or depression.Method:Independent assessors rated audiotaped therapy sessions (early, mid andlate in treatment) in a sample of 132 primary care clients (mean [SD] age=34.8 [11.8],63.6% women), participating in the Prompt Mental Health Care trial. Outcomes weresymptoms of anxiety and depression assessed by patient self-report questionnaires.Structural validity was examined by means of confirmatory and exploratory factoranalyses (CFA/EFA), whereas longitudinal associations with treatment outcome wereexplored by adopting multilevel modeling.Results:No evidence was found for the divergent validity of the constructs competenceand adherence as indicated by a very high correlation between these two subscales inCTACS (0.97). Regarding reliability, ICCs for the mean score of the full competence scaleand its associated subscales were generally good to excellent (0.70–0.80), although thesubscale measuring the quality of the therapeutic relationship was relatively low (0.44).Internal consistency was overall acceptable, but our CFA models did not provide anacceptable fit for the pre-specified one-factor and four-factor solutions. EFA results weredifficult to interpret, with a sub-optimal three-factor solution providing best model fitand only two meaningful factors [CBT specific skills (α=0.82) and session structure(α=0.59)]. Overall, the results indicated no evidence for the scales’ predictive validity.Conclusion:Our findings point to several psychometric problems of the CTACS thatmay limit both its research and clinical utility. The importance of providing empiricalevidence for both reliability and validity aspects of scales are discussed and suggestionsfor future research are provided.