LAUSR

OBJECTIVE Sudden gains are large, rapid, and sustained symptom improvements, and are associated with improved treatment outcomes across a range of mental health problems. Current theories suggest that therapists are required for sudden gains to be sustained, and to result in improved treatment outcomes. We compared the prevalence and consequences of sudden gains in therapist-guided versus self-guided internet-delivered treatments for anxiety and depression. METHOD Samples from four previous randomized controlled trials were analyzed: generalized anxiety disorder (n = 259), panic disorder (n = 109), social anxiety disorder (n = 175), and major depressive disorder (n = 209). The prevalence, timing, and reversal rates of sudden gains were compared across therapist-guided and self-guided groups. Generalized estimating equations were used to examine the impact of guidance level and sudden gain status on posttreatment outcomes. RESULTS Sudden gains were similarly prevalent in therapist-guided and self-guided treatments. In all four diagnostic samples, sudden gains most frequently occurred between Weeks 2 and 3 of treatment, and the rate of reversals did not differ based on the presence of guidance. The association between sudden gains and treatment outcome varied by disorder, such that sudden gains were associated with improved outcomes (irrespective of guidance condition) for participants with social anxiety disorder and major depression, but not generalized anxiety disorder or panic disorder. CONCLUSIONS Sudden gains can occur, and are maintained, during internet-delivered psychotherapy even in the absence of therapist guidance. Furthermore, sudden gains may be associated with different patterns of symptom improvement depending on diagnostic presentation. (PsycInfo Database Record (c) 2022 APA, all rights reserved).