Sudden Gains in Internet-Based Cognitive Behavior Therapy for Body Dysmorphic Disorder.

Sudden gains have been associated with better short- and long-term treatment outcomes in a number of psychiatric disorders. However, no studies to date have evaluated sudden gains in body dysmorphic disorder (BDD). We used data from a previous randomized controlled trial evaluating the efficacy of an Internet-based cognitive-behavior treatment (CBT) for BDD. The sample consisted of 47 adults diagnosed with BDD. We compared the treatment outcomes of sudden gainers vs. gradual gainers (i.e., treatment responders with no sudden gains) and non-sudden gainers (i.e., gradual gainers plus nonresponders) at posttreatment and 3, 12, and 24 months after the end of the treatment. Twelve (25.5%) participants experienced a sudden gain. Compared to non-sudden gainers and to gradual gainers, sudden gainers showed significantly larger improvements on the Yale-Brown Obsessive-Compulsive Scale modified for BDD at posttreatment (g = 1.23 and g = .91, respectively), and at 3-month (g = 1.23 and g = 1.00, respectively), 12-month (g = 1.12 and g = .91, respectively), and 24-month follow-up (g = 1.11 and g = .97, respectively). This translated into higher rates of treatment responders and remitters in the sudden gainers across all time points. The occurrence of sudden gains in Internet-based CBT for BDD is associated with favorable short- and long-term treatment outcomes. This suggests that a sudden improvement during the treatment could be a marker of good prognosis, while non-sudden-including gradual-gainers are more likely to need continued support or booster sessions. Early identification of patients who are not progressing as expected and subsequent tailoring of the delivered intervention has the potential to improve treatment outcomes in this group.