Internet-based cognitive behaviour therapy for social anxiety disorder : from efficacy to effectiveness

Background: Cognitive behaviour therapy (CBT) is an effective, well-established, but not widely available treatment for social anxiety disorder (SAD). Internet-based cognitive behavior therapy (ICBT) has the potential to increase availability and facilitate dissemination of therapeutic services for SAD. However, research is needed to establish efficacy, effectiveness, long-term effects, cost-effectiveness and potential determinants of treatment outcome.

Aims: The present thesis aimed at investigating the following: a) The efficacy of ICBT for SAD in a university setting (Study I), b) the effectiveness of ICBT for SAD in a psychiatric setting (Study II), c) The effects of ICBT for SAD over 5 years (Study III), d) The cost-effectiveness of ICBT for SAD compared to conventional CBT (Study IV), and e) Clinical and genetic determinants of ICBT for SAD in relation to conventional CBT (Study V).

Methods: Two large scale randomised controlled trials (RCTs) were conducted. In the first RCT (Study I), ICBT (n=40) was compared to CBT bibliotherapy (n=40) and a waiting list control (n=40). The second RCT (Study II) was a non-inferiority trial comparing ICBT (n=64) to cognitive behavioural group therapy (CBGT; n=62) in a clinical setting. In Study III, a 5-year follow-up assessment was conducted of participants of Study I. In Study IV, a prospective cost-effectiveness and cost-utility analysis of ICBT compared to CBGT was conducted using a societal perspective. Based on clinical and genetic data collected in Study II, predictors and moderators of treatment outcome of ICBT in relation to CBGT were investigated in Study V.

Results: Study I: ICBT for SAD yielded large effect sizes on measures of social anxiety and demonstrated superiority to waiting list controls and a trend towards superiority of CBT bibliotherapy. Study II: ICBT for SAD was well within the non- inferiority margin compared to CBGT on the primary outcome measure. Study III: Participants receiving ICBT for SAD made further improvements from post-assessment to 1-year follow-up. These improvements were maintained at 5-year follow-up. Study IV: The incremental cost-effectiveness ratio was -7042 USD, suggesting that ICBT compared to CBGT leads to incremental gains to a lower cost. Study V: Demographic, clinical and therapy related factors predicted outcome of CBT. A few clinical factors moderated treatment outcome of ICBT in relation to CBGT. None of the investigated candidate genes had an impact on treatment outcome.

Conclusions: ICBT for SAD is efficacious, effective in a clinical setting, long-term effective and, compared to conventional CBT, cost-effective regardless of willingness to pay. In addition, treatment outcome can be predicted. ICBT for SAD is ready for implementation and dissemination.

List of scientific papers

I. Furmark T, Carlbring P, Hedman E, Sonnenstein A, Clevberger P, Bohman B, Eriksson A, Hållén A, Frykman M, Holmström A, Sparthan E, Tillfors M, Ihrfelt EN, Spak M, Ekselius L, Andersson G. Guided and unguided self-help for social anxiety disorder: Randomised controlled trial. Br J Psychiatry. 2009; 195: 440-7.
https://doi.org/10.1192/bjp.bp.108.060996

II. Hedman E, Andersson G, Ljótsson B, Andersson E, Rück C, Mörtberg E, Lindefors N. Internet-based cognitive behavior therapy vs. cognitive behavioral group therapy for social anxiety disorder: A randomized controlled non-inferiority trial. PLoS ONE. 2011; 6: e18001.
https://doi.org/10.1371/journal.pone.0018001

III. Hedman E, Furmark T, Carlbring P, Ljótsson B, Lindefors N, Andersson G. Five-year follow-up of Internet-based cognitive behaviour therapy for social anxiety disorder. Journal of Medical Internet Research. [Accepted]
https://pubmed.ncbi.nlm.nih.gov/21676694

IV. Hedman E, Andersson E, Ljótsson B, Andersson G, Rück C, Lindefors N. Cost-effectiveness and cost-utility of Internet-based cognitive behavior therapy vs. cognitive behavioral group therapy: Results from a Randomized Controlled Trial. [Submitted]

V. Hedman E, Andersson E, Ljótsson B, Andersson G, Andersson E, Schalling M, Lindefors N, Rück C. Clinical and genetic outcome determinants of Internet- and group-based cognitive behavior therapy for social anxiety disorder. [Submitted]