The HALO trial is designed as a four-armed, assessor-blinded, fidelity-monitored randomized clinical trial. The goal of this randomized controlled study is to investigate the effectiveness of four different psychotherapy programs and to determine which one is most effective in reducing the number of binge-eating episodes in people with the eating disorder Binge Eating Disorder (BED), by directly comparing three intensities of Cognitive Behavioral Therapy-Enhanced against a manualized treatment as usual. Participants will be asked to complete a 21-weeks randomized intervention and participate in follow up assesments.
The HALO trial is a investigator-initiated, four-arm, partially blinded, randomized controlled superiority trial evaluating the effectiveness of three formats and intensities of Cognitive Behavioral Therapy-Enhanced (CBT-E) compared with manualized treatment as usual (TAU) for adults with Binge Eating Disorder (BED). BED is associated with substantial psychiatric and physical morbidity, and despite psychotherapy being the recommended first-line treatment, there is limited high-quality evidence directly comparing different CBT-E delivery formats compared with an active control intervention. The trial aims to determine whether individual CBT-E provides superior clinical outcomes compared with group CBT-E, CBT-E guided self-help, and manualized TAU. A total of 256 participants with a primary diagnosis of BED will be recruited through Danish Mental Health Services and public advertisement. Following informed consent and baseline diagnostic assessments, eligible participants will be randomized in a 1:1:1:1 ratio to one of four treatment arms: (1) individual CBT-E, (2) group CBT-E, (3) therapist-guided CBT-E self-help, or (4) manualized group-based systemic narrative therapy delivered as treatment as usual. All interventions are delivered over a 21-week treatment period. Diagnostic assessments include the Eating Disorder Examination interview to confirm the diagnosis of BED and the Mini International Neuropsychiatric Interview to assess psychiatric comorbidity and study eligibility. The primary outcome is change in binge eating frequency measured using the Eating Disorder Examination Questionnaire. Secondary outcomes include remission from BED assessed by the Eating Disorder Examination interview, overall eating disorder psychopathology (Eating Disorder Examination Questionnaire), psychological well-being (World Health Organization-Five Well-Being Index), work and social functioning (Work and Social Adjustment Scale), anxiety symptoms (State-Trait Anxiety Inventory), and depressive symptoms (Beck Depression Inventory-II). In addition, a broad range of exploratory psychological, clinical, and psychosocial measures will be collected to investigate potential mechanisms of treatment response, predictors of outcome, and moderators and mediators of treatment effects (list of exploratory outcomes is available upon request). These exploratory measures are used only for hypothesis-generating and are not part of the primary efficacy analyses. Post-treatment diagnostic interviews are conducted by blinded outcome assessors. Due to the nature of the psychotherapeutic interventions, participants and therapists cannot be blinded to treatment allocation. Outcome assessors, statisticians, investigators responsible for data analysis, and the trial leadership remain blinded until completion of the primary analyses. To ensure intervention fidelity, therapists receive standardized training and ongoing method-specific supervision throughout the trial. Treatment sessions are video-recorded, and a random sample (10%) will be independently assessed for adherence to the treatment manuals. Assessors receive regular supervision, and inter-rater reliability is monitored throughout the study. Participant safety is monitored throughout the trial. Serious adverse events and clinically significant deterioration are documented according to predefined procedures. Participants identified as having severe depression or elevated suicide risk are managed according to standardized clinical safety procedures. All participants provide written informed consent prior to study participation. Study data are collected and managed using the secure electronic data capture system REDCap, which complies with applicable data protection regulations. Data quality is ensured through standardized assessment procedures, predefined data collection protocols, electronic range and consistency checks, and regular monitoring of study procedures. The primary analysis will follow the intention-to-treat principle, including all randomized participants according to their allocated treatment group regardless of treatment adherence. Continuous outcomes will be analyzed using mixed-effects regression models for repeated measures, while dichotomous outcomes will be analyzed using logistic regression models. Secondary outcome analyses will account for multiple testing where appropriate. Missing outcome data will be handled using likelihood-based mixed models under the missing-at-random assumption, with multiple imputation used for secondary analyses and missing baseline covariates. If substantial evidence suggests that data are Missing Not At Random, sensitivity analyses will be undertaken. A supplementary per-protocol analysis may be conducted if dropout exceeds assumptions used in the sample size calculation. The planned sample size of 256 participants (64 per treatment arm) was based on a priori power calculations assuming a small-to-moderate treatment effect (Cohen's f = 0.20), a two-sided significance level of 0.05, and approximately 85% statistical power in the primary mixed-model repeated measures analysis, while accounting for an anticipated attrition rate of up to 30%. This sample size is expected to provide adequate power to detect clinically meaningful differences between treatment groups. With a planned sample size of 256 participants, the HALO trial is expected to be the largest randomized clinical trial of psychotherapy for BED conducted to date and will provide robust evidence regarding the comparative effectiveness of different CBT-E treatment formats and manualized treatment as usual.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
256
Cognitive Behavioral Therapy Enhanced (CBT-E) (individual) is delivered in 20, 50-minute sessions over 20 weeks, following four stages. Stage 1 (sessions 0-7) consists of twice-weekly sessions to establish treatment momentum, self-monitoring, and regular eating. Stages 2 (sessions 8-9) and 3 (sessions 10-17) are delivered weekly. Stage 2 focuses on reviewing progress and planning the remainder of treatment. In Stage 3, the therapist tailors treatment to the individual by selecting one or more modules addressing (1) body image, (2) dietary restraint, and (3) events, moods, and eating, while also covering setbacks and unhelpful mindsets. Stage 4 (sessions 18-20) is delivered fortnightly and focuses on ending therapy, maintaining progress, and relapse prevention. Each session follows a consistent structure, beginning with in-session weighing, followed by a review of self-monitoring records and homework, agenda setting, and work on the session's goals.
Cognitive Behavioral Therapy Enhanced (group) is group therapy delivered in groups with eight participants and two therapists. The groups are closed, meaning the same eight participants start and finish at the same time. The course consists of one individual session before the group starts, and thereafter 20 weeks of weekly two-hour group sessions. A group manual has been developed by our research group (available upon request), based on 'Cognitive Behavior Therapy Enhanced for Eating Disorders' and 'Overcoming Binge Eating' .
Cognitive Behavioral Therapy (guided self-help) is a therapist-assisted online treatment based on the principles of CBT-E (see above). Participants access the program from home and receive concurrent brief individual support sessions aimed at developing treatment goals, monitoring progress, and encouraging adherence to the program. The treatment begins with a one-hour face-to-face session with a therapist in week 1, followed by eight brief telephone sessions over the course of treatment: weekly calls during the first four weeks (weeks 2, 3, 4), then fortnightly calls for four weeks (weeks 6 and 8), and finally calls every third week until the end of therapy (weeks 11, 14, and 17). The treatment concludes with a one-hour face-to-face session with a therapist in week 20 focused on reviewing progress, maintaining gains, and relapse prevention. The online program was developed by Digital Psychiatry and adapted by our research group to adhere more closely to CBT-E principles.
Systemic Narrative Therapy (group) is the standard outpatient treatment for eating disorders within Mental Health Services of the Capital Region of Denmark. The intervention integrates principles of systemic and narrative psychotherapy and is delivered in groups of approximately eight participants by two therapists. Treatment consists of weekly 3.5-hour sessions over approximately 21 weeks, including individual weighing, a shared meal, and structured group psychotherapy. Therapeutic techniques include reflecting teams, collaborative exploration, and externalizing conversations to help participants separate themselves from the eating disorder and develop alternative narratives. The intervention also includes routine weight monitoring and dietary self-monitoring as part of standard clinical care.
Mental Health Centre Ballerup
Ballerup Municipality, Capital Region, Denmark
RECRUITINGEating Disorder Examination Questionnaire (EDE-Q)
The primary outcome will be binge eating frequency which is measured by the EDE-Q. To meet the abstinence criteria in the current study there should be no binge eating episodes associated with the sense of loss of control in the past month. The EDE-Q is a 28-item questionnaire designed to assess severity of features associated with eating disorders. The EDE- Q has demonstrated good internal consistency, convergent and construct validity and test-retest reliability.
Time frame: Baseline, at end of treatment at 20/21 weeks, at 6 months follow up, at 1 year follow up, at 2 year follow up, at 3 year follow up, at 4 year follow up, at 5 year follow up.
Eating Disorder Examination Interview (EDE-17)
Eating Disorder Examination Interview (EDE-17) is a clinical semi-structured interview used to assess ED diagnoses and symptomatology. The 17th version of the EDE was used. Research shows adequate test-retest reliability for all four subscales of the EDE, and preliminary support has been found for the internal consistency. The interview is considered the gold standard ED assessment tool.
Time frame: At baseline and 4-8 weeks after end of therapy
World Health Organization Well-Being Index (WHO-5)
The WHO-5 is a 5-item self-report measure assessing subjective well-being. Items are rated on a 6-point Likert scale. The measure has demonstrated satisfactory reliability, as well as convergent and factorial validity.
Time frame: Baseline, at end of treatment at 20/21 weeks, at 6 months follow up, at 1 year follow up, at 2 year follow up, at 3 year follow up, at 4 year follow up, at 5 year follow up.
The Work and Social Adjustment Scale (WSAS)
The WSAS assesses the impact of a person's mental health difficulties on their ability to function in terms of work, home management, social leisure, private leisure, and personal or family relationships. This instrument is a 5-item scale. Each of the items is rated on a nine-point Likert scale, from 'Not at all' (0) to 'Severely impaired' (8). The measure shows good validity and reliability.
Time frame: Baseline, at end of treatment at 20/21 weeks, at 6 months follow up, at 1 year follow up, at 2 year follow up, at 3 year follow up, at 4 year follow up, at 5 year follow up.
State-Trait Anxiety Inventory (STAI)
The STAI is a 40-item self-report measure rated on a 4-point Likert scale that assesses two dimensions of anxiety: state anxiety and trait anxiety. In the present study, only the state anxiety subscale (20 items) was administered. Previous research has demonstrated satisfactory reliability and validity of the STAI across both research and clinical settings, supporting its use as a measure of anxiety symptoms.
Time frame: Baseline, at end of treatment at 20/21 weeks and at 6 months follow up.
The Beck Depression Inventory (BDI-II)
The BDI-II is a 21-item self-report measure assessing the severity of depressive symptoms. The instrument was revised in 1996 to align more closely with DSM-IV criteria for depression. Previous research has demonstrated good internal consistency, convergent and discriminant validity, and test-retest reliability, supporting its use as a measure of depressive symptoms.
Time frame: Baseline, at end of treatment at 20/21 weeks and at 6 months follow up.
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