A systematic review of therapist effects: A critical narrative update and refinement to review

Abstract

Objective: To review the therapist effects literature since Baldwin and Imel's (2013) review. Method: Systematic literature review of three databases (PsycINFO, PubMed and Web of Science) replicating Baldwin and Imel (2013) search terms. Weighted averages of therapist effects (TEs) were calculated, and a critical narrative review of included studies conducted. Results: Twenty studies met inclusion criteria (3 RCTs; 17 practice-based) with 19 studies using multilevel modeling. TEs were found in 19 studies. The TE range for all studies was 0.2% to 29% (weighted average = 5%). For RCTs, 1%-29% (weighted average = 8.2%). For practice-based studies, 0.2-21% (weighted average = 5%). The university counseling subsample yielded a lower TE (2.4%) than in other groupings (i.e., primary care, mixed clinical settings, and specialist/focused settings). Therapist sample sizes remained lower than recommended, and few studies appeared to be designed specifically as TE studies as opposed to maximising on the availability of large routine patient datasets. Conclusions: Therapist effects are a robust phenomenon although considerable heterogeneity exists across studies. Patient severity appeared related to TE size. TEs from RCTs were highly variable. Using an overall therapist effects statistic may lack precision, and TEs might be better reported separately for specific clinical settings.

Therapist effects vary significantly across psychological treatment care sectors

“…Notably, the non-NHS sector therapist effects were qualitatively lower than is typically reported in practice-based studies (Baldwin & Imel, 2013;Johns et al, 2019). This is consistent with Johns et al's (2019) (e.g., organizational factors), thereby reducing the relative contribution of the therapist to outcome. Clinical populations in some care contexts may be much more highly selected than in other contexts.…”

Using technology to understand how therapist variables are associated with clinical outcomes in IAPT

“…The authors demonstrated an association between certain utterances and clinical outcome. Given that there is extensive literature that supports the idea that there is significant variance in therapist competence (Johns et al, 2019), it is not surprising that the findings from this study also suggest this. Even studies that have not been conducted in real-world settings report this variance.…”

Facilitative interpersonal skills performance test: Psychometric analysis of a German language version

“…These so-called therapist effects have been found consistently across different patient groups and clinical settings and have been estimated to account for approximately 5% of the variance in patient outcomes (see Johns, Barkham, Kellett, & Saxon, 2019, for a recent review). These so-called therapist effects have been found consistently across different patient groups and clinical settings and have been estimated to account for approximately 5% of the variance in patient outcomes (see Johns, Barkham, Kellett, & Saxon, 2019, for a recent review).…”

“…One of the clearest findings of psychotherapy research in recent years is that therapists differ in their average effectiveness. These so-called therapist effects have been found consistently across different patient groups and clinical settings and have been estimated to account for approximately 5% of the variance in patient outcomes (see Johns, Barkham, Kellett, & Saxon, 2019, for a recent review). In contrast to this consistent support for the relevance of therapist effects, it is less clear which therapist characteristics are responsible for these effects (Heinonen & Nissen-Lie, 2019).…”