Therapist-level moderation of within- and between-therapist process-outcome associations.

Objective: Although higher quality patient-therapist alliance and more positive patient outcome expectation (OE) consistently predict symptomatic/functional improvement in psychotherapy, most research has failed to capture the nuance in these process-outcome relations by parsing them into (i.e., differences between patients treated by the same therapist) and (i.e., differences between therapists' average process/outcome ratings across all patients in their caseloads) components. Moreover, the few studies that have done so have produced mixed results, suggesting the possibility of systematic variability in these associations (i.e., moderators). One potential source of such variability could be providers themselves; that is, different therapists could use these processes to differing therapeutic benefit. This study tested the alliance- and OE-outcome associations at both the within- and between-therapist levels and explored therapist-level moderators of them.

Method: Data derived from 212 adult outpatients treated naturalistically by 42 psychotherapists as part of a randomized trial that compared different case-assignment methods. Patients completed measures of alliance, OE, and outcome repeatedly throughout treatment. Therapist characteristics were assessed at baseline.

Results: Multilevel structural equation models revealed that, at the between-therapist level, only higher alliance quality, but not more optimistic OE, was associated with greater caseload-level improvement. At the within-therapist level, only more optimistic OE, but not higher alliance quality, was associated with patient improvement. Finally, therapists' self-perceived alliance-fostering effectiveness and cognitive-behavioral orientation moderated the within- and between-therapist alliance-outcome associations, respectively.

Conclusion: Results indicate that different therapists use common treatment processes to differing therapeutic benefit, which can inform more personalized clinical practices and trainings. (PsycInfo Database Record (c) 2022 APA, all rights reserved).