A randomized controlled trial of a transdiagnostic Internet intervention for individuals with panic and phobias - one size fits all

Background and objectives Many individuals with anxiety disorders do not receive professional treatment. Internet interventions have shown to be effective in the treatment of anxiety. The present randomized controlled trial was designed to examine the effectiveness of a short-term (4-week) Internet intervention in treating panic disorder, agoraphobia, social anxiety disorder, and specific phobias ('ConfID'). We addressed the questions of whether this transdiagnostic program would affect these disorders to varying degrees and whether there would be moderators of effectiveness. Methods Adults who were recruited in online forums for anxiety underwent an online baseline assessment (N = 179) and were randomized either to the intervention group (ConfID) or the control group (care as usual). Online post-assessment took place 4 weeks later. The primary outcome was assessed with the Beck Anxiety Inventory (BAI); the secondary outcomes targeted the disorder-specific symptoms, depression, and somatization. Results Participants in the intervention group showed a significantly stronger anxiety reduction compared to participants receiving care as usual (small-to-medium effect size between groups in intention-to-treat analysis). The treatment effect was similar for the different disorders and was moderated by participants' attitudes towards Internet interventions. Secondary outcomes yielded effect sizes in the medium range. Limitations Moderate treatment adherence, lack of measures beyond online self-reports, and unavailability of long-term results. Conclusions The study provides further evidence that transdiagnostic Internet interventions are promising in reducing the existing treatment gap in individuals with panic disorder and phobias. Results extend previous findings by showing that significant effects can also be reached by comprehensive short-term programs and that the effects might be moderated by participants' attitudes towards Internet interventions.