Internet-based Treatment for Patients Suffering From Severe Functional Somatic Disorders

The aim of this multi-center, two-armed, randomized controlled trial is to assess the effect of a novel internet-based therapist-assisted treatment program "One step at a time" designed for the treatment of patients with moderate to severe functional somatic disorder (FSD). The trial will enroll 166 patients with FSD who will be randomized (1:1) to either the experimental condition (14 weeks' treatment with "One step at a time") or the active control condition ("GetStarted"), which is a non-guided internet-based treatment program for patients with FSD. The trial will include patients aged 18-60 years with an established single/oligo-organ or multi-organ FSD diagnosis, with a duration of minimum 6 months. The primary outcome measures will be based on self-reported physical health (SF-36 PPH) and treatment satisfaction (CGI-I). The trial will be considered effective if a higher proportion of patients in the experimental condition report a clinically significant outcome compared with patients in the active control condition at the 3-month follow-up after treatment.