Prevention and treatment of social anxiety disorder in adolescents: mixed method randomised controlled trial of the guided online intervention SOPHIE.

Social anxiety symptoms are highly prevalent in adolescents and negatively impact their social and academic functioning, highlighting the need for effective low-threshold interventions. This randomised controlled trial evaluated the guided online intervention SOPHIE for adolescents (N = 133; 11-17 years) with social anxiety disorder (SAD; treatment) or subclinical social anxiety (indicated prevention) compared to care-as-usual control condition and qualitatively explored their experiences. Outcomes were assessed at baseline, mid-intervention (4 weeks), post-intervention (8 weeks) and 5-month follow-up and analysed using linear mixed-effects models. SOPHIE did not significantly reduce social anxiety symptoms post-intervention but showed a significant between-group effect at follow-up (d = 0.67, 95%CI [0.32;1.02]). Subgroup analyses by diagnostic condition showed a significant between-group effect at follow-up in the subclinical social anxiety (d = 1.53, 95%CI [1.74;0.41]) but not in the SAD condition. Social functioning significantly improved at post-intervention and follow-up, with medium to large effects (post: d=-0.73, 95%CI [-1.08; -0.37]; follow-up: d=-0.32, 95%CI [-0.66; 0.02]). Qualitative interviews post-intervention revealed that participants found the intervention beneficial, although some found exposure exercises challenging and desired additional support. Very heterogeneous needs emerged regarding the guidance provided during the programme. Low-threshold online interventions for adolescents with social anxiety may be effective, particularly as an indicated prevention approach.