THE RELATIONSHIP BETWEEN GROUP TREATMENT INTEGRITY AND OUTCOME: A SYSTEMATIC REVIEW

Introduction: Treatment integrity, also defined as treatment fidelity, is described as the extent to which treatment was implemented according to a specific theoretical model (Perepletchikova, 2011). Several theoretical approaches have provided a definition of treatment integrity as a multidimensional concept. According to Waltz et al. (1993), treatment integrity is composed of two different dimensions: adherence, which represents the extent to which therapist uses specified procedures (namely performing all prescribed tasks and activities), and competence, the skill of the therapist in delivering the treatment (namely proper therapeutic strategies delivered with appropriate timing). Perepletchikova & Kazdin (2005) proposed the addition of a third dimension, the differentiation, which refers to whether the treatments under investigation differ from each other along critical dimensions (namely implementing procedures prescribed by the manual of the treatment under examination and avoiding procedures prescribed for other manualized treatments). Adherence and treatment differentiation are closely related; thus, a measure of adherence can be sufficient to also determine treatment differentiation (Waltz et al., 1993). Treatment integrity ought to relate to therapeutic change, but research on the topic yielded mixed results in individual setting: some studies found a positive relationship between treatment integrity and positive outcome, while other studies did not find any relationship or found a negative relationship. In group psychotherapy research, studies on this topic are also quite scarce (Esposito et al., 2020). This systematic literature review aimed at studying whether adherence and/or competence is associated to group treatment outcome. Methods: We followed PRISMA 2020 (Page et al., 2021) indications for systematic reviews and conducted electronic and full-text searches on three different databases: PsycInfo, PsycArticles and Scopus. Studies research was based on the following keywords: (“integrity” OR “fidelity”) AND (“group psychotherapy” OR “group therapy” OR “group counseling” OR “group intervention” OR “group treatment”) AND (“outcome” OR “effect” OR “impact” OR “effectiveness” OR “efficacy) AND (“therapist” OR “counselor” OR “psychotherapist” OR “psychologist” OR clinician”) AND (“adherence” OR “adherent” OR “adhering” OR “adhere”) AND (“competence” OR “competency” OR “competencies” OR “competent”). Inclusion criteria for the selection of studies were the following: 1) group treatment outcome assessment; 2) treatment delivered by clinical psychologists and/or psychotherapists; 3) treatment integrity assessment; 4) exploration of the relationship between group treatment integrity and outcome. Research yielded 2949 studies. Thirtynine studies were removed as duplicates and 2168 were excluded based on title and/or abstract. Thus, 704 were identified as eligible and 656 of these were excluded as they did not meet inclusion criteria, namely did not assess treatment integrity, or did not refer to a group treatment outcome evaluation, or the treatments were not delivered by clinical psychologists/psychotherapists. Moreover, 31 studies which analysed both integrity and group treatment effectiveness were excluded as they did not study the specific relationship between group outcome and treatment integrity. At the end of the screening phase, 17 studies fulfilled the inclusion criteria, and they were analysed for the following steps. Results: All the group treatments evaluated in the 17 studies were manualized and based on cognitive-behavioural, mentalization-based or systemic theoretical models. Most of the studies assessed both adherence and competence, while one study focused only on competence and five only on adherence. Regarding integrity assessment, seven studies relied on observer-raters measures, two relied on clinician-report evaluation tools, and eight studies relied on multiple sources. Regarding the relationship between treatment integrity and treatment outcome, nine studies found that at least one of the integrity dimensions was related to treatment outcome, while one found that competence was related to outcome when delivery of treatment was also adherent; one study found that integrity was effective in influencing positive outcome with clients with severe symptoms, another study found that adherence was associated to positive outcome only when evaluated by therapists, and one study found that there was a relationship only when integrity was assessed by therapists. Only two studies found no relationship between treatment integrity and outcome. Conclusions: Overall, treatment integrity seems to be more clearly associated with positive outcomes in group interventions than in individual setting, although the number of studies included in this review is quite small and only some treatment integrity dimensions showed a positive relationship with outcome. Moreover, findings showed that the relationship between treatment integrity and outcome is investigated in treatments oriented by specific theoretical models (e.g., cognitivebehavioral) and not in other (e.g. psychodynamic models), and that many methods of assessment (e.g. clinician-report, patient self-report) are frequently used to assess treatment integrity, sometimes showing mixed Results: Furthermore, findings showed that treatment dimensions have a different impact on outcome. Finally, it is worth noting that a number of studies were excluded as they did not analyse the relationship between integrity and group outcome, but they evaluated or guaranteed treatment integrity as a prerequisite for the research. In this perspective, and from a clinical and methodological point of view, the assessment of treatment integrity remains a relevant topic for the research in group psychotherapy and the evaluation of its relationship with treatment outcome should become an essential part of research protocols in order to provide useful indications for the clinical practice and therapists’ training.