(PS10-60) Within-patient increases in perceived treatment credibility as a predictor of improvement in naturalistic psychotherapy

Abstract Text:

Background: Patients’ perceptions of treatment credibility reflect their judgement of how personally suitable, logical, and helpful a proposed intervention seems. Research indicates that greater early patient-perceived treatment credibility predicts better posttreatment outcomes (for a meta-analysis, see Constantino et al., 2018). However, most of this work has examined between-patient differences in treatment credibility at one time before or during treatment. Therefore, less is known about whether and to what degree treatment credibility changes over time and if such within-person shifts predict improvement in symptoms/functioning. The present study tested these novel questions in the context of naturalistic psychotherapy for varied mental health concerns.

Method: Data derived from a sample of 218 adult patients who received naturalistic outpatient psychotherapy from 48 community therapists as part of a randomized trial that examined different case assignment methods (Constantino et al., 2021). Although therapy was naturalistic and could follow any theoretical model, most therapists reported a strong cognitive behavioral orientation. Patients completed a measure of treatment credibility (i.e., Credibility/Expectancy Questionnaire; Devilly & Borkovec, 2000) and symptomatic/functional impairment severity (i.e., Treatment Outcome Package; Kraus et al., 2005) at baseline and bi-weekly through up to 16 weeks of therapy.

Results: Multilevel models (repeated measures nested within patients nested within therapists) revealed there was no average change pattern for patient-perceived credibility across treatment (slope = 0.02, p = .22). However, there was significant patient-level variability in credibility change (variance = 0.01, p < .001), indicating that individual differences in the size and direction of such change could still predict treatment outcomes. Indeed, when controlling for baseline problem severity and case assignment condition, within-person increases in patient-perceived credibility were associated with greater reductions in symptomatic/functional impairment (B = -2.03, p = .04). Additionally, at the between-patient level, higher average credibility perceptions were associated with lower posttreatment symptomatic/functional impairment (B = -0.12, p = .02).

Discussion: Consistent with the one prior study of which we are aware on this topic (Wester et al., 2024), the present results suggest that within-patient shifts in perceived treatment credibility may represent an active change ingredient that can predict subsequent improvement. That being said, our results also show that increasing perceptions of treatment credibility are not necessarily the norm in naturalistic treatment settings. Therefore, in the face of waning or stagnant patient treatment credibility perceptions, therapists could consider incorporating explicit credibility fostering strategies (e.g., highlighting research support for treatment strategies, promoting and highlighting early symptom improvement, personalizing the rationale) in order to help maximize patient improvement.