Supplementary Material for: Long-Term Effectiveness of Cognitive Behavioral Therapy in Routine Outpatient Care for Youth with Anxiety Disorders

Introduction: This study examines the long-term effectiveness of standardized Cognitive Behavioral Therapy (CBT) (≥ 2 years after therapy) in routine care of youth (11.95 yrs; SD= 3.04 yrs) with primary anxiety disorder (AD). Methods: Two-hundred and ten children with any AD as primary diagnosis, were included and received evidence-based CBT. Diagnoses, severity of diagnoses and further outcome variables of symptoms and of functioning were assessed before (baseline) and at 3 assessment points after treatment in child- and caregiver report: After last treatment session (POST), 6 months (6MONTHS-FU) and > 2 years (mean 4.31; SD 1.07 years) later (long-term follow-up, LT-FU). Results: At POST, 61.38 % showed total remission of all and any ADs. At LT-FU, remission rate was 63.64%. Compared to baseline, ratings of severity, anxiety, impairment/burden and life quality improved significantly after CBT in child-and caregiver report. All pre-post/FU-improvements and global success ratings were stable in child- (Pre-Post: Hedges' g = 3.57; Pre-6MONTHS-FU: Hedges' g = 3.43; Pre- LT-FU: Hedges' g = 2.34) and caregiver report (Pre-Post: Hedges' g = 2.00; Pre-6MONTHS-FU: Hedges' g = 2.31; Pre- LT-FU: Hedges' g Hedges' g = 2.31) across all POST- and FU-assessment points. Some outcomes showed further significant improvement; no deterioration was found. Benchmark comparison indicated that present effect correspond to, or even exceed, effect sizes of previous meta-analysis. Conclusions: Stable long-term effects of CBT for youth with ADs, comparable to those results from efficacy studies, were achieved in a routine practice setting, applying treatment manuals tested in RCTs.