Long-term effectiveness of cognitive behavioral therapy (CBT) for children and adolescents in routine care

Abstract Background Cognitive behavioral therapy (CBT) is one of the most widely established treatments for mental disorders in children and adolescents and is empirically supported across a wide range of disorders, including evidence from routine care. However, evidence on long-term maintenance of effects in routine outpatient care is still limited, particularly across diagnostic groups. This study examines the long-term, cross-diagnostic effectiveness of CBT in children and adolescents treated under routine outpatient care conditions. Methods Analyses are based on pre-existing routine outcome monitoring data from 1225 patients (mean age = 14. 00 years, SD = 3. 24) receiving CBT, collected between 2017 and 2025. Symptoms were assessed using the parent- and patient-reported Strengths and Difficulties Questionnaire (SDQ) at pre-treatment, post-treatment and at 6-, 12- and 24-month follow-ups. Additional self-rated treatment-success ratings were collected at follow-up (covering expectations fulfilled, perceived helpfulness, problem recurrence and perceived change). Effectiveness was described using group means as well as clinical significance. Pre- to post- and pre- to follow-up changes were analysed using paired Wilcoxon signed-rank tests. Associations between follow-up SDQ scores and self-rated treatment success were examined using partial Spearman correlations controlling for baseline SDQ. Results Across both parent- and patient-reported SDQ assessments, total difficulties and problem subscales showed significant improvements from pre- to post-treatment and from pre-treatment to all follow-up time points. Effect sizes were consistently moderate-to-large (rᵣb = 0. 59–0. 77), with sustained effects up to 24 months. Higher follow-up SDQ difficulties were associated with lower self-rated treatment success across multiple follow-up ratings, with strongest associations observed for problem recurrence and change compared to before treatment. Sensitivity analyses restricted to participants in the clinical range at baseline (SDQ ≥ 17) yielded consistent results. Conclusions Routine outpatient CBT for children and adolescents was associated with meaningful symptom improvements that persisted up to two years after treatment. Clinically significant change analyses indicated that while many patients showed reliable improvement, a substantial proportion remained classified as unchanged according to conservative criteria. Subjective follow-up ratings were consistent with standardized symptom outcomes, supporting the perceived durability of treatment success under routine care conditions in a diagnostically heterogeneous sample. Trial registration Not applicable. This study is an observational analysis of routinely collected data. The analysis plan was preregistered at PsychArchives (https: //doi. org/10. 23668/psycharchives. 21444).