Assessing the alliance–outcome association adjusted for patient characteristics and treatment processes: A meta-analytic summary of direct comparisons

The alliance is widely recognized as a robust predictor of posttreatment outcomes. However, there is a debate regarding whether the alliance is an epiphenomenon of intake characteristics and/or treatment processes occurring over the course of treatment. This meta-analysis aimed to synthesize the evidence on this issue. We identified 125 effect sizes in 60 independent samples (6,061 participants) of studies that reported alliance-outcome correlations as well as parallel intake or process characteristics. We examined the impact of these potential confounds on the alliance-outcome correlations. We meta-analyzed the studies estimates by computing omnibus effects models as well as multivariate models. We identified 3 variable types that were used to adjust the alliance-outcome correlations: (a) intake characteristics (k = 35); (b) simultaneous processes, such as adherence or competence (k = 13); and (c) both intake and simultaneous processes (k = 24). We found moderate alliance-outcome correlations with or without adjustments for intake and simultaneous processes (range from r = .23 to r = .31). Our results provide robust empirical evidence for the assertion that the alliance-outcome association is an independent process-based factor. Findings suggest that alliance is positively related to outcome above and beyond the studied patient intake characteristics and treatment processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).