Credibility and expectancy of smartphone-based cognitive behavioral therapy among adults with body dysmorphic disorder

Background: Few patients receive cognitive behavioral therapy, the gold-standard for body dysmorphic disorder (CBT-BDD). Smartphones can make evidence-based interventions, like CBT-BDD, more accessible and scalable. A key question is: how do patients view it? Low credibility and expectancy would likely translate to low uptake and engagement outside of research settings, diminishing the impact. Thus, it is important to understand patients' beliefs about digital CBT-BDD.Methods: We compared credibility and expectancy in a coach-guided app-based CBT-BDD trial (N = 75) to a previous in-person CBT-BDD trial (N = 55). We further examined the relationship of perceptions of digital CBT-BDD to baseline clinical and demographic factors and dropout.Results: Credibility did not differ between the in-person (M = 19.3) and digital (M = 18.3) trials, p = .24. Ex-pectancy for improvement was moderately higher for in-person (M = 58.4) than digital (M = 48.3) treatment, p = .005. In the digital trial, no demographic variables were associated with credibility or expectancy. Better BDD-related insight and past non-CBT BDD therapy were associated with greater expectancy. Credibility was asso-ciated with lower likelihood of dropout.Discussion: Digital CBT-BDD was regarded as similarly credible to in-person CBT-BDD but with lower expectancy. Tailored expectancy-enhancing strategies could strengthen this novel approach, particularly among those with poorer insight and without prior BDD treatment.