Do treatment responders maintain their gains following a randomized clinical trial comparing an acceptance-based behavior therapy to applied relaxation for generalized anxiety disorder?

To examine the maintenance effects of acceptance-based behavior therapy (ABBT) and applied relaxation (AR) for generalized anxiety disorder (GAD) 46 adults (69.6% female, 82.6% White) with high end-state functioning following an RCT comparing ABBT to AR were re-assessed at 12- and 24-month follow-up. End-state functioning was based on post-treatment scores within one standard deviation of the mean on three of five outcome measures [Clinician Severity Rating (CSR), Hamilton Anxiety, Penn State Worry Questionnaire (PSWQ), Depression Anxiety Stress Scale stress subscale (DASS-Stress), and State-Trait Anxiety Inventory (STAI)]. At 12 months, 93.8% of high endstate responders in ABBT and 95.5% in AR had maintained gains. At 24 months, 71.4% of responders from ABBT and 83.3% from AR maintained gains. Mixed-effects regression models revealed a significant effect for Time and Condition for DASS-Stress but not for Condition X Time. There was also a significant time effect for PSWQ, indicating PSWQ and DASS-Stress scores increased across follow-up. The rate of increase did not differ across conditions. Non-significant, small effects were found for all other outcomes indicating that symptoms did not significantly change across follow-up regardless of condition. While the results are limited by dropout rates, clients receiving ABBT or AR appear to maintain gains over long-term follow-up.