Interventions
The therapist-guided IERITA used in this study had been optimized based on feasibility studies,The comparison condition TAU was chosen to control for some nonspecific aspects of treatment (eg, time, monitoring) and ensure patient safety. The TAU was delivered in both conditions within regular CAMHS care by community clinicians (external to the research group) and typically involved supportive therapy sessions every 2 weeks. Thus, participants in IERITA plus TAU typically had contact with 2 clinicians (face-to-face contact with a community clinician and online contact with the IERITA therapist). TAU was enhanced by weekly self-rated assessments and as needed follow-ups from the research team (when deterioration in mental health was detected) (eMethods in 