Comparison of the Working Alliance in Blended Cognitive Behavioral Therapy and Treatment as Usual for Depression in Europe: Secondary Data Analysis of the E-COMPARED Randomized Controlled Trial

Background: Increasing interest has centered on the psychotherapeutic working alliance as a means of understanding clinical change in digital mental health interventions in recent years. However, little is understood about how and to what extent a digital mental health program can have an impact on the working alliance and clinical outcomes in a blended (therapist plus digital program) cognitive behavioral therapy (bCBT) intervention for depression. Objective: This study aimed to test the difference in working alliance scores between bCBT and treatment as usual (TAU), examine the association between working alliance and depression severity scores in both arms, and test for an interaction between system usability and working alliance with regard to the association between working alliance and depression scores in bCBT at 3 -month assessments. Methods: We conducted a secondary data analysis of the E -COMPARED (European Comparative Effectiveness Research on Blended Depression Treatment versus Treatment -as -usual) trial, which compared bCBT with TAU across 9 European countries. Data were collected in primary care and specialized services between April 2015 and December 2017. Eligible participants aged 18 years or older and diagnosed with major depressive disorder were randomized to either bCBT (n=476) or TAU (n=467). bCBT consisted of 6-20 sessions of bCBT (involving face-to-face sessions with a therapist and an internet-based program). TAU consisted of usual care for depression. The main outcomes were scores of the working alliance (Working Alliance Inventory -Short Revised-Client [WAI-SR-C]) and depressive symptoms (Patient Health Questionnaire -9 [PHQ-9]) at 3 months after randomization. Other variables included system usability scores (System Usability Scale -Client [SUS -C]) at 3 months and baseline demographic information. Data from baseline and 3 -month assessments were analyzed using linear regression models that adjusted for a set of baseline variables. Result