Somatosensory amplification moderates the efficacy of internet-delivered CBT for somatic symptom distress in emerging adults: Exploratory analysis of a randomized controlled trial

Objective: While studies mainly provide positive evidence for the efficacy of internet-delivered cognitive-behavioral therapy (ICBT) for various persistent somatic symptoms, it remains largely unclear for whom these interventions work or not. This exploratory analysis aimed to identify moderators for the outcome between ICBT for somatic symptom distres and a waitlist control group (WL) in a vulnerable target group of emerging adults. Methods: Based on data from a randomized controlled trial on 156 university students with varying degrees of somatic symptom distress who were allocated to either an eight-week, therapist guided ICBT (iSOMA) or to the WL, we examined pretreatment demographic characteristics, health-related variables (e.g., somatic symptom duration), mental distress (e.g., depression, anxiety) and cognitive-emotional factors (emotional reactivity, somatosensory amplification) as candidate moderators of the outcome, somatic symptom distress (assessed by the Patient Health Questionnaire, PHQ-15) from pre- to posttreatment. Results: Somatosensory amplification (assessed by the Somatosensory Amplification Scale, SSAS) moderated the outcome in favor of iSOMA (B = −0.17, SE = 0.08, p = 0.031), i.e., higher pretreatment somatosensory amplification was associated with better outcome in the active compared to the control intervention. No significant moderation effects were found among demographic characteristics, health-related variables, or mental distress. Conclusion: Our findings suggest that an internet-delivered CBT for somatic symptom distress should be preferred over no active treatment particularly in individuals with moderate to high levels of somatosensory amplification, which as a next step should be tested against further treatments and in clinical populations. Trial registration: German Clinical Trials Register (DRKS00014375).