Alliance in internet-based interventions: A systematic review and correlation multilevel meta-analysis

Internet-based interventions (IBIs) offer scalable, low-threshold treatment options for mental health care. The therapeutic alliance is a key collaborative quality in psychological therapy, yet its role and structure in IBIs remain debated.

This correlational meta-analysis synthesizes the overall alliance-outcome association (k = 82 effect sizes nested in s = 40 independent samples; n = 2,864 participants) and its variability across the Working Alliance Inventory subscales using meta-analytic multilevel models.

The overall association was small to moderate (r = .21) confirming the relevance of alliance in digital contexts. Subscale-specific analyses showed that task (r = .25) and goal (r = .19) were more predictive of treatment outcomes than bond (r = .12), highlighting a shift toward cognitive-collaborative components in IBIs. Even exploratory in nature, none of the examined moderators (diagnosis, alliance rater, face-to-face contact, therapeutic approach, publication year, and country) systematically influenced the effect size.

The results confirm the robustness of the prediction of the alliance on outcomes observed in the general literature and at the same time point to the particular qualities of using IBIs. Future work is needed to adapt the conceptualization and assessment of alliance in IBI. (PsycInfo Database Record (c) 2026 APA, all rights reserved).