Mechanism Engagement as a Potential Evidence-Based Approach to Personalized Treatment Termination

Objective: This study explores whether early change on a putative mechanism maintaining symptoms can serve a proximal indicator of response to prompt discontinuation. Method: Participants (N = 70) with heterogeneous anxiety and depressive disorders were enrolled in a pilot sequential multiple assignment randomized trial (SMART). Patients received 6 sessions of skill modules from the Unified Protocol and then underwent a second-stage randomization to either receive the remaining 6 sessions (Full duration) or discontinue treatment (Brief duration). All participants completed weekly self-report measures of anxiety and depressive symptoms (Overall Anxiety Severity and Interference Scale; Overall Depression Severity and Interference Scale) and distress aversion (Multidimensional Experiential Avoidance Questionnaire) for the full treatment window (i.e., 12 weeks). We used structural equation modeling to test (1) if distress aversion demonstrated significant variability during the first-stage randomization and (2) if distress aversion during the first-stage randomization predicted second-stage changes in anxiety and depression. Results: Participants demonstrated significant variability in first-stage distress aversion. Latent distress aversion slopes significantly predicted latent second-stage anxiety slopes, whereas latent distress aversion intercepts significantly predicted latent second-stage depression slopes. Conclusions: These results suggest that it may be possible to use early mechanism engagement as a trigger that prompts personalized termination. Shorter courses of care have the potential to reduce patient costs and increase the mental health service system’s capacity.