One size does not fit all: Examining heterogeneity and identifying moderators of the alliance-outcome association.

Although the alliance-outcome association is one of the most consistent findings in psychotherapy research, it is also highly heterogeneous. Little is known about the factors explaining this variability, and consequently there is a lack of adequate knowledge about how to utilize this association to improve treatment. The present study had the following objectives: (a) to examine the associations between within- and between-individual variability in alliance and outcome, controlling for previous symptomatic levels; (b) to examine the duration of the alliance-outcome association; and (c) to examine potential moderators of the alliance-outcome association. A total of 547 patients treated in a primary care psychotherapy setting in Chile were randomly assigned to 5 feedback conditions. The alliance-outcome association was analyzed using multilevel models, disentangling changes in alliance within-individuals from alliance between-individuals. Patient and therapist characteristics were examined as potential moderators. Findings suggest that patients who reported a better early alliance also reported a better outcome. Furthermore, patients reporting time-specific improvement in alliance also reported a greater reduction in symptoms. The unique effect of alliance on outcome at one point in time is maintained for a period of 2 weeks. Patients with more severe symptoms and longer treatments benefited more from a good alliance. Therapists identifying themselves as more integrative in their treatment orientation were able to better utilize good alliances for treatment success. Finally, the size of the alliance-outcome association can be manipulated by feedback to therapists.