During the last two decades, Internet-delivered cognitive behavior therapy (ICBT) has been tested in hundreds of randomized controlled trials, often with promising results. However, the control groups were often waitlist, care-as-usual or attention control. Hence, little is known about the relative efficacy of ICBT as compared to face-to-face cognitive behavior therapy (CBT). In addition, the long-term effects of ICBT is largely unknown.

In this presentation a systematic review and meta-analysis, which included 1418 participants, will be presented. Out of the 2078 articles screened, a total of 20 studies met all inclusion criteria. These included studies on social anxiety disorder, panic disorder, depression, body dissatisfaction etc. Results showed a pooled effect size at post-treatment of Hedges g = 0.05 (95% CI, -0.09 to 0.20), indicating that ICBT and face-to-face treatment produced equivalent overall effects.

We also reviewed studies in which the long-term effects of guided ICBT were investigated. Following a new set of literature searches in PubMed and other sources meta-analytic statistics were calculated for 14 studies involving a total of 902 participants, and an average follow-up period of three years. The duration of the actual treatments was usually short (8-15 weeks). The pre-to follow-up (>2 yrs) effect size was Hedge’s g = 1.52, but with a significant heterogeneity. The average symptom improvement across studies was 50%.

While the overall results indicate equivalence, there have been few studies of the individual psychiatric and somatic conditions so far, and for the majority, guided ICBT has not been compared against face-to-face treatment. Thus, more research, preferably with larger sample sizes, is needed to establish the general equivalence of the two treatment formats. While effects may be overestimated, it is likely that therapist-supported ICBT can have enduring effects.