Investigating the Efficacy of In Vivo Exposure as an Additive Element to Cognitive Behavior Therapy for Eating Disorders: A Multiple-Baseline Design across Behaviors

Abstract

Cognitive behavior therapy (CBT) has proven to be an effective treatment for many individuals with eating disorders. On the other hand, a substantial proportion of eating disorder patients fail to recover through CBT and other tested treatments. To improve the efficacy of the approach, it may be helpful to add treatment elements that are effective for partially related conditions, such as anxiety disorders. Therapist-assisted in vivo exposure (IVE), one of the most supported interventions for anxiety disorders, may reduce distress and increase self-efficacy for a range of foods and eating, weight, and shape situations that patients with eating disorders fear and avoid. To investigate the efficacy of IVE as an additive element to CBT, a multiple-baseline design across behaviors was conducted using patients at a university-based outpatient eating disorder clinic. For each participant, distress and self-efficacy ratings were examined at multiple time points before and after each IVE session. Changes in distress and self-efficacy ratings for the variables targeted by each IVE were compared to variables not targeted by the exposure session. As predicted, visual inspection of mean and level generally found a decrease in distress and an increase in self-efficacy ratings following IVE sessions; however, this pattern of change also often occurred for variables that were not directly targeted by the IVE. According to visual inspection of trend, target variables generally did not exhibit predicted changes in slope following IVE sessions. Analyses using within-subject Cohen’s d effect sizes tended to converge with findings from visual inspection of mean, while the adjusted R2 values computed via Allison’s mean plus trend difference were similar to results from visual inspection of trend. Although limitations with the study’s design preclude conclusions about whether IVE contributed to reductions in anxiety or improvements in self-efficacy specific to target variables, the results suggest that challenging IVE sessions were perceived as valuable by some participants. Further research is warranted to understand the efficacy of IVE, a potentially valuable additive component to CBT for eating disorders.