Long-term efficacy of cognitive behavioural therapy for generalized anxiety disorder: A 2-8-year follow-up of two randomized controlled trials

Abstract

Anxiety disorders are the most prevalent mental disorders globally, with generalized anxiety disorder (GAD) being one of the most common among them. While GAD can be effectively treated with bona fide cognitive behavioural therapy (CBT), research on its long-term efficacy is scarce. This study examined the long-term efficacy of CBT for GAD in terms of statistical symptom reduction and clinically significant change. A follow-up of 93 GAD patients, 2-8 years post-treatment from two randomized controlled implementation trials, was conducted. Outcome measures included two disorder-specific outcomes and three general mental health outcomes. Statistical symptom reduction was assessed using piecewise linear growth models, and clinically significant change was evaluated based on Jacobson and Truax's (1991) criteria. Results indicated that treatment gains were maintained from six-months post-treatment to long-term follow-up for all outcome measures except depressive symptoms, which increased during this period. Clinically significant change analysis showed that 57 %-77 % of participants were categorised as recovered 2-8 years post-CBT. This study provides insights into treatment durability 2-8 years post-treatment. Treatment success was largely maintained, with more than half to three-quarters of patients categorised as recovered, supporting the sustained efficacy of CBT for GAD.

Keywords: Cognitive behavioural therapy; Follow-up; Generalized anxiety disorder; Long-term efficacy; Randomized controlled trial.