Effectiveness of transdiagnostic Internet cognitive behavioural treatment for mixed anxiety and depression in primary care

Background: Internet-delivered cognitive behavioural treatment (iCBT) has been shown to be effective for the combined treatment of depression and anxiety in randomised controlled trials. The degree to which these findings generalise to patients in primary care awaits further investigation.

Methods: Using an open-trial design, we investigated adherence to, and effectiveness of a 6-lesson therapist-assisted iCBT program for mixed anxiety and depression for patients (n = 707) who completed the program under the supervision of primary care clinicians (general practitioners, psychologists and other allied health professionals). Primary outcome measures were the PHQ-9 (depression), GAD-7 (generalised anxiety), K-10 (distress), WHODAS-II (disability), mini-SPIN (social anxiety) and panic disorder severity scale self-report version (PDSS).

Results: Adherence to the iCBT program was modest (47.3%), but within-subjects effect sizes ranged from medium (0.51 for PDSS) to large (1.20 for PHQ-9).

Limitations: The lack of control group, limited post-treatment data due to drop-out, and short follow-up period.

Conclusions: iCBT is an effective treatment for mixed depression and anxiety when delivered in primary care settings. Methods to increase adherence are needed to optimise the benefits to patients.