Therapist effects in yearlong psychodynamic therapy: An exploratory study.

A large body of research indicates that therapists can have a strong impact on treatment outcome, but little is known about the relationship between therapist effects and treatment phase. Our objective was to examine the interactive effect of therapist effectiveness and treatment phase on the outcome of 1 year of dynamic therapy. Therapists' effectiveness scores were defined as the extent of change for each therapist on the OQ-45 scores across their clients at five time points. The sample included 24 therapists who conducted psychodynamic therapy with 65 clients in a naturalistic setting. A three-level hierarchical linear model was applied. In accordance with the hypotheses, a significant main effect was found for effectiveness (estimate = 1.69, p < .05), for the two-way interactions between effectiveness and time (estimate = 1.36, p < .01), and for effectiveness and initial severity of symptoms (estimate = -0.02, p < .05). Simple slope analysis was conducted showing that among the less effective therapists, no significant change in outcome was found as time progressed; among the more effective therapists, outcome improved as time progressed. In addition, therapists were more influential in the treatments of clients with low initial severity. Our findings lend some support to the notion that therapist effects become increasingly influential as therapy progresses. The findings highlight the need for further research into changes in the magnitude of therapists' effect in various phases of therapy. Furthermore, the severity level of the initial symptoms of the client should be taken into account.