Long-term effectiveness of transdiagnostic cognitive-behavioural therapy for anxiety and depression in primary care: the PsicAP-CV trial

INTRODUCTION: Anxiety disorders and depression represent a global public health challenge due to their high prevalence, severely impacting quality of life (QoL) and functioning, and imposing a massive economic burden on public systems. This study evaluates the effectiveness of a group transdiagnostic cognitive behavioural therapy (TD-CBT) protocol through a stepped wedge cluster randomised controlled trial (SW-CRT) in Spanish primary care (PC). METHODS: The sample consisted of 316 PC patients (73.4% female; mean age=44 years) with mild-to-moderate symptoms of anxiety and depression. An immediate intervention group was compared with a delayed intervention group (three months on a waiting list). Patients were assessed at pre-treatment, post-treatment, and 3- and 9-month follow-ups using mixed linear models. RESULTS: Results revealed significant reductions in anxiety and depression symptoms with large effect sizes (d > 1.2) that remained stable up to 9 months. Improvements in QoL and functioning were heterogeneous, showing sustained long-term gains in work and family domains, but not in broader QoL or social functioning. No significant differences were found in clinical efficacy between groups, with solid reliable recovery rates (∼50%) and minimal deterioration. However, delayed access to treatment significantly increased long-term dropout rates (64.2% in the delayed group vs. 44.0% in the immediate group at 9 months). CONCLUSIONS: In conclusion, group TD-CBT is an effective and safe intervention offering robust functional and symptomatic recovery. Crucially, while delayed treatment does not reduce clinical efficacy for completers, immediate access is essential to maximize patient retention and optimize resources in the public system.