Rapid Response to Day Hospital Treatment in Bulimia Nervosa and Purging Disorder (CBT-RR)

Rapid Response to Day Hospital Treatment in Bulimia Nervosa and Purging Disorder: A Randomized Controlled Trial of an Intervention to Facilitate Early Symptom Change

Treatments for bulimia nervosa (BN) have relatively high rates of nonremission and relapse, meaning that improving treatments is a high priority in this area. Rapid response to treatment -cessation of binge eating and vomiting symptoms within the first weeks of treatment - is a robust predictor of improved post-treatment outcomes and lower relapse rates, but no study has tried to facilitate rapid response as a means of improving treatment outcomes. The present study responds to this gap in the literature by testing a 4-session CBT-based individual intervention for rapid response (i.e., "CBT-RR"), designed to augment standard day hospital (DH) treatment for BN and Purging Disorder (PD) by focusing on strategies and skills for rapid symptom interruption. CBT-RR will be compared to a matched-intensity augmentative motivational interviewing (MI) intervention. Participants will be recruited from a hospital-based day program for eating disorders, and will be randomly assigned to one of the two conditions in addition to the DH as usual. participants will be assessed at pre-intervention, post-intervention, week 4 of DH, post-DH, and 6 months follow-up. It is hypothesized that compared to those who receive MI, patients who receive CBT-RR will be more likely to exhibit a rapid response to day hospital treatment (i.e., </= 3 binge eating and/or vomiting episodes in the first 4 weeks). It is further hypothesized that patients who receive CBT-RR will exhibit fewer binge eating and/or vomiting episodes at post-DH and at 6-month follow-up. Potential mediators and moderators of these hypothesized treatment effects will be examined on an exploratory basis, including self-efficacy, motivation, and hope (potential mediators), and emotion regulation, depression, cognitive psychopathology of eating disorders, and working alliance with the therapist (potential moderators).

Cognitive behaviour therapy (CBT) is the most empirically supported treatment for bulimia nervosa (BN) and related disorders, yet approximately 1/3 of completers do not remit, there is a substantial treatment attrition rate, and 1/3 of remitted patients will relapse within the first 2 years. Improving CBT is an important research prerogative. Motivational interviewing (MI) is an augmentative intervention that has been investigated to improve CBT, but reviews indicate that it is not efficacious with eating disorders. The failure of MI with eating disorders has led to consideration that focusing on early behaviour change might be a more productive therapeutic strategy. Rapid response to treatment for eating disorders has been reliably identified as a prognostic indicator in eating disorders. For BN and similar disorders, rapid response is the rapid reduction of binge eating, vomiting, and dietary restriction during the first few weeks of treatment. Numerous studies have indicated that patients who rapidly respond to treatment are significantly more likely to be remitted at post treatment and significantly less likely to relapse, compared to those who respond more slowly. No preexisting clinical, demographic, personality or other factors have clearly emerged to account for this effect. Given that rapid response has clear prognostic importance, and given that research has failed to identify mechanisms driving this finding, this study seeks to determine whether rapid response can be facilitated clinically using a targeted intervention designed to provide patients with specific behavioural skills to decrease their bulimic symptoms rapidly. Improving remission and relapse rates is a high priority in the eating disorders research field. the investigators already know that cognitive and behavioural strategies have efficacy for eating disorders, but existing treatments need improvement. Rapid response is an area that has been frequently described and has clear prognostic importance and no clear mechanism accounting for why some patients rapidly respond, suggesting that perhaps rapid response could be facilitated if patients are provided with the skills, mindset, and support to do so. However, no study to date has sought to answer this question and determine whether rapid response can be facilitated in order to improve patient prognoses. Thus, this study seeks to examine whether rapid response to day hospital treatment can be facilitated clinically using an augmentative CBT based intervention targeting early symptom change. The CBT intervention will be compared to a matched-intensity motivational interviewing (MI) intervention. The rationale for using MI is because MI is frequently used to augment standard treatments, it provides an active treatment comparison, and because the rationale for the present study emerged partly from research aimed at understanding some of the limitations of MI in treating eating disorders. Thus, MI provides a theoretically-driven comparison group. It is predicted that individuals who receive CBT (versus MI) will be more likely to be classified as rapid responders, and will have fewer bulimic symptoms at post-day hospital and 6-month follow-up. As well, it is hypothesized that changes in self-efficacy, motivation, or hopefulness may help to account for these findings.

In this arm, participants receive the Cognitive behavior therapy (CBT) intervention as an augmentative treatment to standard day hospital treatment as usual.

In this arm, participants receive the Motivational Interviewing intervention as an augmentative treatment to standard day hospital treatment as usual.

The CBT intervention is a 4 session (1 hour each) individual psychotherapy intervention that uses a manualized treatment protocol developed by the investigators. It uses standard CBT for eating disorders interventions, including orientation to the CBT model, psychoeducation, commitment and goal setting, behavioral strategies for normalizing eating and reducing bulimic symptoms, planning, and homework. 1-2 sessions are delivered before starting day hospital treatment, and the remaining sessions are delivered in the first weeks of day hospital.

The MI intervention is a 4 session (1 hour each) individual psychotherapy intervention that uses a manualized treatment protocol (Carter & Bewell-Weiss, 2012). It uses standard MI for eating disorders interventions, including decisional balance, exploring values, readiness and confidence rules, and MI communication strategies. 1-2 sessions are delivered before starting day hospital treatment, and the remaining sessions are delivered in the first weeks of day hospital.

Rapid response is a binary outcome variable (yes/no) of early bulimic symptoms. Rapid responders exhibit a total of three or fewer binge and/or vomit and/or laxative episodes in the first four weeks of day hospital treatment for eating disorders.

Bulimic symptoms (binge eating and/or vomiting and/or laxative use) will be totalled for each 4 week period and changes modelled over time at the following time points: Baseline, first 4 weeks of day hospital, last 4 weeks of day hospital, and months 1-6 in follow-up.

Each of the following: Baseline, first 4 weeks of day hospital, last 4 weeks of day hospital, and months 1-6 in follow-up.

Outcome is a binary outcome variable, remitted (yes/no). Remitted patients have one or fewer binge and/or vomit and/or laxative episodes in the last 4 weeks of day hospital treatment. Non-remitted patients have 2 or more episodes in this same period. Day hospital stays are expected to consist of an average of 8 weeks of treatment.

Relapse is a binary outcome variable (yes/no). Relapsed patients have an average of 4 or more binge and/or vomit and/or laxative use episodes per month for three consecutive months, beginning in the first 6 months after discharge from day hospital program. Non-relapsed patients have bulimic symptoms below this threshold.

Changes in self-efficacy will be modelled across several time points (baseline, session 2, week 4 of day hospital, and post-day hospital). Changes in self-efficacy from baseline to the 4th week in day hospital treatment will also be examined as a potential mediator of the effects of treatment on rapid response. Self-efficacy will be measured using the Readiness and Motivation Questionnaire (Geller et al., 2013). Day hospital stays are expected to consist of an average of 8 weeks of treatment.

Each of the following: Baseline, Session 2 (on average the week before starting Day Hospital or Day Hospital week 1), Day Hospital Week 4, End of Day hospital (average=8 weeks)

Changes in motivation will be modelled across several time points (baseline, session 2, week 4 of day hospital, and post-day hospital). Changes in motivation from baseline to the 4th week in day hospital treatment will also be examined as a potential mediator of the effects of treatment on rapid response. Motivation will be measured using the Readiness and Motivation Questionnaire (Geller et al., 2013). Day hospital stays are expected to consist of an average of 8 weeks of treatment.

Each of the following: Baseline, Session 2 (on average the week before starting Day Hospital or Day Hospital week 1), Day Hospital Week 4, End of Day hospital (average=8 weeks)

Changes in hope will be modelled across several time points (baseline, session 2, week 4 of day hospital, and post-day hospital). Changes in hope from baseline to the 4th week in day hospital treatment will also be examined as a potential mediator of the effects of treatment on rapid response. Hope will be measured using an investigator-constructed questionnaire. Day hospital stays are expected to consist of an average of 8 weeks of treatment.

Each of the following: Baseline, Session 2 (on average the week before starting Day Hospital or Day Hospital week 1), Day Hospital Week 4, End of Day hospital (average=8 weeks)

Emotion regulation skills at baseline will be examined as a potential moderator of treatment response.

Weight-based self-esteem at baseline will be examined as a potential moderator of treatment response.

Working alliance with study therapist will be examined as a potential moderator of treatment response.

Inclusion Criteria: Diagnosis of bulimia nervosa or other specified feeding and eating disorder (OSFED) purging disorder Body mass index of 19.0 or higher Has accepted day hospital eating disorder treatment at the Toronto General Hospital Eating Disorder Day Hospital Program No previous treatments at the Toronto General Hospital Eating Disorder Day Hospital Program in the previous 5 years Can read and write English fluently. Exclusion Criteria: Current imminent suicidality Current manic episode Current psychosis Current medical instability as assessed by program medical team.

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