The number of people experiencing difficulties with eating disorders has sharply increased since COVID-19, and are more responsible for loss of life over and above any other mental health difficulty (Beat, 2021; Community Practitioner, 2021). Living with an eating disorder severely impacts the quality of life for the individual and carers, making access to effective treatments of the utmost importance.
Cognitive Behavioural Therapy for eating disorders (CBT-ED) is the recommended treatment for adults with bulimia nervosa and binge eating disorder (NICE, 2017). This is supported by evidence demonstrating its effectiveness when compared with other types of therapy (Linardon et al., 2017; Slade et al., 2018).
There is a gap in service provision regarding the number of treatment sessions offered. Currently, services routinely offer guided self-help or 20 sessions CBT-ED. Some recent research has investigated the effectiveness of a new 10 session CBT-ED programme, with promising findings for its effectiveness (Waller et al., 2019; Waller et al., 2018; Pellizzer et al., 2019a; Pellizzer et al., 2019b). However, our understanding of specific moderators is limited.
Understanding the moderating relationship of specific components within CBT-ED is important, as personalising treatment in this way can improve response to treatment (Fairburn et al., 2009). Two potential moderators may be baseline motivation regarding the therapeutic change, and body image work (Sanfacon et al., 2020), although there is little robust evidence to support this.
Wade and colleagues (2021) investigated this issue in their research. They aimed to: “compare the efficacy of two forms of 10 session CBT-ED for patients with a BMI of more than 17.5… and to conduct an exploratory investigation of moderators”. One form of CBT-ED emphasised early behaviour change and body image referred to as CBT-T. The other form of CBT-ED included motivational work and no content on body image, referred to as CBTm.
The participants were 98 individuals from the Flinders University Services for Eating Disorders (FUSED) who had been referred. Inclusion criteria were: aged 15 or older, BMI >17.5, DSM-5 diagnosis of an eating disorder, agreed to allow FUSED to communicate with their GP, and agreed to commit to therapy. The diagnoses represented were 5% with anorexia nervosa, 69% with bulimia nervosa, 5% with binge eating disorder, and 21% with otherwise specified feeding and eating disorder. Exclusion criteria were: current rapid weight loss, suicidal or self-harm intention, psychosis or substance dependence, already receiving psychotherapy, difficulty speaking or understanding English.
Participants were allocated to either CBT-T or CBTm through block randomisation. Therapists saw participants in both conditions control for therapist effects. The primary outcome measured was global eating psychopathology, by using the EDE-Q. Secondary outcomes that were measured included disordered eating behaviours, BMI, clinical impairment, negative affect, remission and good outcome. The moderators investigated were motivation, body avoidance and body checking. Outcome measures were completed at five different time points (baseline, 4-, 10-, 14-, and 22-weeks post-randomisation).
Linear mixed-model analyses were the statistical analyses used to analyse the effectiveness of each treatment and for the moderation analyses.
The two treatment arms were reasonably balanced for baseline characteristics. For the CBT-T group, 59% received the allocated treatment, and 60% for the CBTm group.
- No significantly different between-group effects across the different time points, or interactions between group and time were found.
- Large effect size improvements were found for disordered eating, impairment, depression, anxiety and stress.
- Remission was achieved in 22/43 in the CBT-T group, and 14/22 in the CBTm group.
- Participants with lower readiness to change in CBTm had significantly greater decreases in disordered eating over first and 3-month follow-up compared to those with low motivation in CBT-T.
The authors concluded that:
- There was no difference in the rate of change between CBT-T and CBTm across the first four sessions.
- As participants with lower levels of motivation in the CBTm group had significantly greater decreases in disordered eating over time compared with low motivation participants in CBT-T, people with lower readiness to change might benefit from the incorporation of motivational work in CBT-ED.
Strengths and limitations
Overall, it was good to see that the study had clear research aims and hypotheses, and the study addresses a gap in the literature in relation to session length for CBT-ED. It was a strength in the methodology for therapist effects to be controlled to minimise the outcomes obtained from the study, particularly as the study was comparing two different interventions.
There are some limitations:
- Firstly, although the sample was representative of individuals in Australia seeking outpatient treatment for eating disorders, the inclusion criteria of a diagnosis of an eating disorder and BMI > 17.5 meant that there was a variety in the presentation of eating disorders. Future research would benefit from selecting specific eating disorders, as there are nuances between the disorders that could impact the influence of moderators.
- Secondly, the study was underpowered to detect the effect size differences needed for the moderation analysis, as the authors acknowledge. Therefore, the findings should be interpreted with caution.
- Finally, the study did not use a control group, which is important for isolating the role of particular variables. For this study, in particular, this may have been an important addition: as the CBTm group had belief work as well as the CBT-T group, using a control group may have helped with the moderator analyses and provided support for the role of body image work.
Implications for practice
The study has important clinical implications, particularly for the role of moderators in the treatment of eating disorders. Understanding the role of moderators is important for therapeutic work, as it can help to see what treatment works best for who (Kraemer, 2016). It can help to personalise treatment, which has the subsequent benefits for improving therapeutic rapport which is all important for treatment outcomes.
This study highlighted the importance of including motivational work for CBT-ED for those with initially lower motivation to change to improve therapeutic outcomes. Therefore, this may be an important routine integration for practitioners working with adults with eating disorders using CBT.
The wider implications relate to service protocols. Although we must be cautious due to the methodological limitations and results, both CBT-T and CBTm had outcomes comparable to the effects of longer therapies. Longer versions of the study are required to strengthen this claim, but this is an important service implication due to the new reports of the rise in eating disorders across all age groups since the start of COVID-19 pandemic, and government policy on reducing obesity with introducing calorie counting on menus being likely to trigger eating disorders. In addition, there is significant pressure on the NHS regarding long waiting lists. An effective intervention that shortens treatment duration almost by half may be an important integration for services, as this may reduce waiting time for those in need.
Statement of interest
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Beat (2021). How many people have an eating disorder in the UK? Retrieved from: https://www.beateatingdisorders.org.uk/get-information-and-support/about-eating-disorders/how-many-people-eating-disorder-uk/
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