Objective: No previous studies have evaluated the efficacy of Internet-based cognitive–behavioral therapy (ICBT) among children below age 13 years screened at the population level. This study was an open, 2 parallel–group randomized controlled trial (RCT), stratified by sex, that compared ICBT with telephone coaching vs an educational control.
Method: Altogether 465 children (mean age = 11.5 years, SD = 1.0 years, 71.4% girls) were randomly allocated to ICBT or psychoeducation. The 10-week ICBT included weekly digital material and exercises and weekly telephone calls. Assessments comprised child and parent reports on anxiety (Screen for Child Anxiety Related Emotional Disorders questionnaire [SCARED]), impacts of anxiety, quality of life, comorbidity, and parental mental health assessed at baseline and at 6-month follow-up.
Results: The ICBT group yielded significantly higher improvement in primary outcomes (SCARED total scores) when compared with control group in the child reports (p = .04, Cohen d = 0.17) but not in the parent reports (p = .41, d = 0.03). The ICBT group had significantly higher improvement in several secondary measures of outcome, including child-reported SCARED generalized anxiety (p = .047, d = 0.09), separation anxiety (p = .004, d = 0.40), social anxiety (p = .007, d = 0.27), the parent-reported Strengths and Difficulties Questionnaire total score (p = .002, d = 0.22), emotional difficulties (p = .02, d = 0.20), hyperactivity (p = .003, d = 0.19), and quality of life (p = .02, d  = 0.16).
Conclusion: When children were screened at the population level for anxiety and enrolled in this RCT study of ICBT combined with telephone guidance, they showed efficacy in improving anxiety and quality of life. These findings are encouraging when developing early population-based intervention strategies for childhood anxiety.