Evaluation of internet-based CBT for social anxiety disorder

Abstract: Background: Social anxiety disorder (SAD) is a common mental disorder, causing considerable distress and functional disability for affected individuals and places a significant economic burden on society. However, few receive treatment due to several barriers such as low treatment availability, stigma and fear. The effectiveness of cognitive behavioural therapy (CBT) is well established, and recent innovations in e-health such as internet-based CBT (ICBT) may significantly increase access to effective care. Several trials have demonstrated that ICBT is both efficacious and cost-effective. However, before disseminating ICBT into the mental health care system, it is essential to evaluate its clinical effectiveness to study whether it works as expected when delivered as routine care in a naturalistic setting. Aims: The aims of this doctoral project were to evaluate the clinical effectiveness of ICBT in the treatment of SAD, to assess its non-inferiority against the standard treatment and to identify outcome predictors. Methods: Study I (N = 654), II (N = 446) and IV (N = 764) were longitudinal cohort studies of patients having been treated as part of routine care during 2009-2014. Within-group effects and the influence of potential predictor variables on treatment response and adherence were estimated using multilevel modelling. In Study III (N = 126), non-inferiority of ICBT was evaluated against standard treatment (face-to-face cognitive behavioural group therapy; CBGT) four years after treatment using a randomised controlled trial (RCT) design, assessing changes in symptoms of SAD and yearly societal costs. Results: In all studies, large (d = 0.8-1.3) improvements were observed after ICBT. Beneficial effects (i.e. reduced symptoms of social anxiety and co-morbid depressive symptoms and increased health-related quality of life) of treatment were maintained up to four years. When compared against standard treatment, ICBT was at least as long-term effective and cost-effective; although the estimated treatment cost of ICBT amounted to only 17% of the cost of CBGT, both interventions were equally effective and led to similar yearly societal cost reductions. Improvement slopes varied significantly between patients. High levels of treatment credibility and adherence were associated with better treatment response. Furthermore, higher illness severity predicted greater improvement but was also related to worse follow-up status. Conclusion: ICBT can be successfully implemented in routine clinical care and is at least as effective and cost-effective as standard treatment for SAD, both short- and long-term. With its potential to significantly improve access to specialised mental healthcare, ICBT represents an important step forward in modernising healthcare systems through increased use of e-health.