Guided internet-based treatment for anxiety and depression in Norwegian primary care: a randomized non-inferiority...

Meta-analyses suggest that therapist-guided internet-based cognitive behavioural therapy (iCBT) is as effective as face-to-face CBT for anxiety and depression, yet its non-inferiority in routine primary care settings is scarcely examined. We examined the non-inferiority of the therapist-guided program "Assisted self-help" (AS-iCBT) compared to treatment as usual within the Norwegian Prompt Mental Health Care (TAU-PMHC).

A pragmatic, parallel-group, randomized controlled non-inferiority trial with 1:2 (AS-iCBT: TAU-PMHC) allocation was conducted. Participants (n = 390, 37.4% of eligible) were adults considered for PMHC admission for anxiety and/or mild to moderate depression between October 2021, and December 2023. TAU-PMHC was predominantly individual face-to-face therapy (78%). Primary outcomes were change in symptoms of depression (PHQ-9) and anxiety (GAD-7) at six months follow-up. Symptom trajectories were analysed using latent growth curve models with robust maximum likelihood estimator (MLR), employing a non-inferiority margin of d > -0.30.

Both groups showed clinically significant reductions in PHQ-9 (d _w: AS-iCBT = -1.15, TAU-PMHC = -1.26) and GAD-7 (d_w: AS-iCBT = -0.92, TAU-PMHC = -1.11) at 6 months follow-up. However, AS-iCBT was not non-inferior to TAU-PMHC for primary outcomes (PHQ-9: d _b = -0.11 [95% CI -0.40; 0.19]; GAD-7: d_b = -0.19 [95% CI -0.43; 0.04]) and several secondary outcomes. Non-inferiority was demonstrated in client-rated but not therapist-rated alliance. AS-iCBT required approximately 46% less therapist time per client than TAU-PMHC.

AS-iCBT did not meet the pre-defined criteria for non-inferiority compared to usual PMHC care for most outcomes. Nevertheless, AS-iCBT showed potential as a resource-efficient treatment option, requiring less therapist time while achieving clinically significant improvements. Further research should focus on optimizing its implementation, particularly for anxiety-related conditions.