Effectiveness of ICBT for Severe Health Anxiety in Clinical Psychiatry.

Severe health anxiety is a prevalent disorder, leading to considerable distress and is associated with high societal costs. Internet-based cognitive behaviour therapy is a method to improve access to evidence-based psychological treatments and it has shown to be efficacious in the treatment of severe health anxiety in several randomized controlled trials. However, there is limited knowledge of its effectiveness and application in clinical psychiatric care. The aim of this study is to evaluate the clinical effectiveness of internet-based cognitive therapy for severe health anxiety within regular psychiatric care. The investigators will conduct at a cohort-study with a pretest-posttest design investigating consecutively recruited patients from May 2018 to April 2021 in an outpatient psychiatric clinic specialised in delivering ICBT. The treatment content has been successfully tested in previous efficacy studies and will be delivered during 13 weeks. The primary outcome measure will be the gold standard SHAI and a within-group design with repeated measures will be used in the primary analysis. It is estimated that 400 patients will receive treatment during this period and thus be included in the study, if consenting. It is hypothesized that ICBT will be associated with a significant reduction in health anxiety as measured with SHAI, both after treatment and at six-month follow-up. The effect size is expected to be somewhat smaller than in research trials but still moderate to large (d \> 0.5).