A broad v. focused digital intervention for recurrent binge eating: a randomized controlled non-inferiority trial

Behavior Change Techniques Within Digital Interventions for the Treatment of Eating Disorders: Systematic Review and Meta-Analysis

BACKGROUND

Previous systematic reviews of digital eating disorder interventions have demonstrated effectiveness at improving symptoms of eating disorders; however, our understanding of how these interventions work and what contributes to their effectiveness is limited. Understanding the behavior change techniques (BCTs) that are most commonly included within effective interventions may provide valuable information for researchers and developers. Establishing whether these techniques have been informed by theory will identify whether they target those mechanisms of action that have been identified as core to changing eating disorder behaviors. It will also evaluate the importance of a theoretical approach to digital intervention design.

OBJECTIVE

This study aims to define the BCTs within digital self-management interventions or minimally guided self-help interventions for adults with eating disorders that have been evaluated within randomized controlled trials. It also assessed which of the digital interventions were grounded in theory and the range of modes of delivery included.

METHODS

A literature search identified randomized controlled trials of digital intervention for the treatment of adults with eating disorders with minimal therapist support. Each digital intervention was coded for BCTs using the established BCT Taxonomy v1; for the application of theory using an adapted version of the theory coding scheme (TCS); and for modes of delivery using the Mode of Delivery Ontology. A meta-analysis evaluated the evidence that any individual BCT moderated effect size or that other potential factors such as the application of theory or number of modes of delivery had an effect on eating disorder outcomes.

RESULTS

Digital interventions included an average of 14 (SD 2.6; range 9-18) BCTs. Self-monitoring of behavior was included in all effective interventions, with Problem-solving, Information about antecedents, Feedback on behavior, Self-monitoring of outcomes of behavior, and Action planning identified in >75% (13/17) of effective interventions. Social support and Information about health consequences were more evident in effective interventions at follow-up compared with postintervention measurement. The mean number of modes of delivery was 4 (SD 1.6; range 2-7) out of 12 possible modes, with most interventions (15/17, 88%) being web based. Digital interventions that had a higher score on the TCS had a greater effect size than those with a lower TCS score (subgroup differences: χ21=9.7; P=.002; I²=89.7%) within the meta-analysis. No other subgroup analyses had statistically significant results.

CONCLUSIONS

There was a high level of consistency in terms of the most common BCTs within effective interventions; however, there was no evidence that any specific BCT contributed to intervention efficacy. The interventions that were more strongly informed by theory demonstrated greater improvements in eating disorder outcomes compared to waitlist or treatment-as-usual controls. These results can be used to inform the development of future digital eating disorder interventions.

TRIAL REGISTRATION

PROSPERO CRD42023410060; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=410060.

A randomized controlled trial of an online single session intervention for body image in individuals with recurrent binge eating

OBJECTIVE

Theoretical models highlight body image disturbances as central to the maintenance of eating disorders, with empirical evidence finding negative body image to be a robust predictor of treatment nonresponse, relapse and symptom persistence. Accessible, scalable, and inexpensive interventions that can effectively target negative body image across the eating disorders are needed. We developed an online single session intervention (SSI) for negative body image and evaluated its acceptability and efficacy in a randomized controlled trial in individuals with recurrent binge eating.

METHOD

Participants with recurrent binge eating were randomly assigned to the SSI (n = 99) or a waitlist (n = 101). Assessments were conducted at baseline, 4 week follow-up, and 8 week follow-up.

RESULTS

81% of participants accessed the SSI, demonstrating reasonable uptake. However, issues with attrition were apparent; a 32% study dropout rate was observed at posttest, while a 58% dropout rate was observed at follow-up. 87% of participants who completed satisfaction measures would recommend the SSI. SSI participants experienced greater improvements in negative body image at both 4 (d = -0.65) and 8 week (d = -0.74) follow-up. Significant between-group effects were also observed on most other secondary symptom measures, though no differences were found for motivations and help-seeking beliefs and intentions.

CONCLUSION

Body image-focused self-guided SSIs for recurrent binge are largely accepted by those who are retained in the trial, but are associated with significant attrition. Although SSIs are not intended to replace standard treatment, they may help with short-term symptom management and could play an important role in eating disorder care.

PUBLIC SIGNIFICANCE

Single session interventions (SSI) are a potentially accessible, scalable, and cost-effective way to deliver evidence-based treatment content to people with eating disorders. This study shows that an online (SSI) designed to target body image among people with recurrent binge eating is accepted and produced short-term symptom relief.

Advancing randomized controlled trial methodologies: The place of innovative trial design in eating disorders research

Randomized controlled trials can be used to generate evidence on the efficacy and safety of new treatments in eating disorders research. Many of the trials previously conducted in this area have been deemed to be of low quality, in part due to a number of practical constraints. This article provides an overview of established and more innovative clinical trial designs, accompanied by pertinent examples, to highlight how design choices can enhance flexibility and improve efficiency of both resource allocation and participant involvement. Trial designs include individually randomized, cluster randomized, and designs with randomizations at multiple time points and/or addressing several research questions (master protocol studies). Design features include the use of adaptations and considerations for pragmatic or registry-based trials. The appropriate choice of trial design, together with rigorous trial conduct, reporting and analysis, can establish high-quality evidence to advance knowledge in the field. It is anticipated that this article will provide a broad and contemporary introduction to trial designs and will help researchers make informed trial design choices for improved testing of new interventions in eating disorders. PUBLIC SIGNIFICANCE: There is a paucity of high quality randomized controlled trials that have been conducted in eating disorders, highlighting the need to identify where efficiency gains in trial design may be possible to advance the eating disorder research field. We provide an overview of some key trial designs and features which may offer solutions to practical constraints and increase trial efficiency.

Predictors, mediators, and moderators of response to digital interventions for eating disorders: A systematic review

OBJECTIVE

Digital interventions show promise as an effective prevention or self-management option for eating disorders (EDs). However, it remains unclear how, for whom, and through what mechanisms they work in this population, as a synthesis of outcome predictors, moderators, and mediators is lacking. This systematic review synthesized empirical research investigating predictors, mediators, and moderators of response to digital interventions for EDs.

METHOD

Six databases were searched (PROSPERO CRD42022295565) for studies that assessed predictors, moderators, or mediators of response (i.e., uptake, drop-out, engagement, and symptom level change) to a digital prevention or treatment program for EDs. Variables were grouped into several overarching categories (demographic, symptom severity, psychological, etc.) and were synthesized qualitatively across samples without a formally diagnosed ED (typically prevention-focused) and samples with a formally diagnosed ED (typically treatment-focused).

RESULTS

Eighty-six studies were included. For studies recruiting samples without a formal diagnosis (n = 70 studies), most predictors explored were statistically unrelated to outcome, although participant age, baseline symptom severity, confidence to change, motivation, and program engagement showed preliminary evidence of prognostic potential. No robust moderators or mediators were identified. Few studies recruiting samples with a formal diagnosis emerged (n = 16), of which no reliable predictors, moderators, or mediators were identified.

DISCUSSION

It remains unclear how, for whom, and under what circumstances digital programs targeting EDs work. We offer several recommendations for future research with the aim of advancing understanding of client characteristics and intervention elements that signal success from this intervention modality.

PUBLIC SIGNIFICANCE

Digital interventions have shown potential as an effective, scalable, and accessible intervention option for EDs. However, responsiveness varies, so advancing understanding of predictors, mediators, and moderators of outcome to digital interventions for EDs is needed. Such knowledge is important for enabling safe and efficient treatment matching, and for informing future development of effective digital interventions.

Exploration of the individual and combined effects of predictors of engagement, dropout, and change from digital interventions for recurrent binge eating

OBJECTIVE

Our ability to predict responsiveness to digital interventions for eating disorders has thus far been poor, potentially for three reasons: (1) there has been a narrow set of predictors explored; (2) prediction has mostly focused on symptom change, ignoring other aspects of the user journey (uptake, early engagement); and (3) there is an excessive focus on the unique effects of predictors rather than the combined contributions of a predictor set. We evaluated the univariate and multivariate effects of outcome predictors in the context of a randomized trial (n = 398) of digitally delivered interventions for recurrent binge eating.

METHOD

Thirty baseline variables were selected as predictors, ranging from specific symptoms, to key protective factors, to technological acceptance, and to online treatment attitudes. Outcomes included uptake, early engagement, and remission. Univariate (d) and multivariate (D) standardized mean differences were calculated to estimate the individual and combined effects of predictors, respectively.

RESULTS

At the univariate level, few predictors produced an effect size larger than what is considered small (d > .20) across outcomes. However, our multivariate approach enhanced prediction (Ds = .65 to 1.12), producing accuracy rates greater than chance (63%-71% accuracy). Less than half of the chosen variables proved to be useful in contributing to predictions in multivariate models.

CONCLUSION

Findings suggest that accuracy in outcome prediction from digitally delivered interventions may be better driven by the aggregation of many small effects rather than one or several largely influential predictors. Replication with different data streams (sensor, neuroimaging) would be useful.

PUBLIC SIGNIFICANCE

Our ability to predict who will and will not benefit from digital interventions for eating disorders has been poor. We highlight the viability of a multivariate approach to outcome prediction, whereby prediction may be better driven by the aggregation of many small effects rather than one or a few influential predictors.

Investigating change in network structure of eating disorder symptoms after delivery of a smartphone app-based intervention

BACKGROUND

Eating disorder (ED) research has embraced a network perspective of psychopathology, which proposes that psychiatric disorders can be conceptualized as a complex system of interacting symptoms. However, existing intervention studies using the network perspective have failed to find that symptom reductions coincide with reductions in strength of associations among these symptoms. We propose that this may reflect failure of alignment between network theory and study design and analysis. We offer hypotheses for specific symptom associations expected to be disrupted by an app-based intervention, and test sensitivity of a range of statistical metrics for identifying this intervention-induced disruption.

METHODS

Data were analyzed from individuals with recurrent binge eating who participated in a randomized controlled trial of a cognitive-behavioral smartphone application. Participants were categorized into one of three groups: waitlist (n = 155), intervention responder (n = 49), and intervention non-responder (n = 77). Several statistical tests (bivariate associations, network-derived strength statistics, network invariance tests) were compared in ability to identify change in network structure.

RESULTS

Hypothesized disruption to specific symptom associations was observed through change in bivariate correlations from baseline to post-intervention among the responder group but were not evident from symptom and whole-of-network based network analysis statistics. Effects were masked when the intervention group was assessed together, ignoring heterogeneity in treatment responsiveness.

CONCLUSION

Findings are consistent with our contention that study design and analytic approach influence the ability to test network theory predictions with fidelity. We conclude by offering key recommendations for future network theory-driven interventional studies.

Effects of Participant's Choice of Different Digital Interventions on Outcomes for Binge-Spectrum Eating Disorders: A Pilot Doubly Randomized Preference Trial

It is unclear whether offering individuals a choice between different digital intervention programs affects treatment outcomes. To generate initial insights, we conducted a pilot doubly randomized preference trial to test whether offering individuals with binge-spectrum eating disorder a choice between two digital interventions is causally linked with superior outcomes than random assignment to these interventions. Participants with recurrent binge eating were randomized to either a choice (n = 77) or no-choice (n = 78) group. Those in the choice group could choose one of the two digital programs, while those in the no-choice group were assigned a program at random. The two digital interventions (a broad and a focused program) took 4 weeks to complete, were based on cognitive-behavioral principles and have demonstrated comparable efficacy, but differ in scope, content, and targeted change mechanisms. Most participants (79%) allocated to the choice condition chose the broad program. While both groups experienced improvements in primary (Eating Disorder Examination Questionnaire global scores and number of binge eating episodes over the past month) and secondary outcomes (dietary restraint, body image concerns, etc.), no significant between-group differences were observed. The two groups did not differ on dropout rates, nor on most indices of intervention engagement. Findings provide preliminary insights towards the role of client preferences in digital mental health interventions for eating disorders. Client preferences may not determine outcomes when digital interventions are based on similar underlying principles, although larger trials are needed to confirm this.

Understanding the role of positive body image during digital interventions for eating disorders: Secondary analyses of a randomized controlled trial

Despite growing interest in the possible link between positive body image and eating disorder (ED) symptoms, little is known about what role this adaptive construct plays in ED treatment. This study investigated whether: (1) interventions principally designed to target ED psychopathology also lead to improvements in positive body image indices (i.e., body appreciation, functionality appreciation, and body image flexibility); (2) changes in ED symptoms correlate with changes in positive body image, both concurrently and prospectively; and (3) baseline positive body image levels moderate the degree of symptom improvement. Secondary analyses from a randomized controlled trial on digital interventions for EDs (n=600) were conducted. Intervention participants reported greater increases in the three positive body image constructs than the control group (ds=0.15-0.41). Greater pre-post reductions in ED psychopathology and binge eating were associated with greater pre-post improvements in positive body image indices. However, earlier reductions in ED psychopathology and binge eating did not predict later improvements in positive body image at follow-up. None of the positive body image constructs at baseline moderated degree of symptom change. Standard ED interventions can cultivate a more positive body image, although this is not explained by earlier symptom reduction. Understanding the mechanisms through which ED interventions enhance positive body image is needed.