Thesis

Treatment outcome in binge eating disorder: moving ahead! Cognitive behavior therapy and dialectical behavior therapy compared Mirjam Lammers

Colofon Treatment outcome in binge eating disorder: moving ahead! Cognitive behavior therapy and dialectical behavior therapy compared Copyright © 2024 Mirjam Lammers All rights reserved. No part of this thesis may be reproduced, stored, or transmitted in any way or by any means without the prior permission of the author, or when applicable, of the publishers of the scientific papers. Layout: Douwe Oppewal Cover and design: Cathrien van de Veerdonk I Veerdonk-ontwerp Print: Ipskamp Printing, Enschede The studies described in this thesis were supported by mental health service ‘GGNet’.

Treatment outcome in binge eating disorder: moving ahead! Cognitive behavior therapy and dialectical behavior therapy compared Proefschrift ter verkrijging van de graad van doctor aan de Radboud Universiteit Nijmegen op gezag van de rector magnificus prof. dr. J.M. Sanders, volgens besluit van het college voor promoties in het openbaar te verdedigen op dinsdag 8 oktober 2024 om 16.30 uur precies door Mirjam Wilhelmina Lammers geboren op 2 oktober 1968 te Geldrop

Promotoren: Prof. dr. T. van Strien Prof. dr. G.J.M. Hutschemaekers Prof. dr. R.D. Crosby (University of North Dakota, Verenigde Staten) Copromotor: Dr. M.S. Vroling (GGNet Amarum) Manuscriptcommissie: Prof. dr. A.E.M. Speckens (voorzitter) Prof. dr. H.W. Hoek (Rijksuniversiteit Groningen) Dr. A.E. Dingemans (GGZ Rivierduinen Eetstoornissen Ursula)

Voor mijn ouders

7 Contents Chapter 1 General introduction, appendix - 9 diagnostic criteria binge eating disorder DSM-5 Chapter 2 Predictors of outcome for cognitive behaviour therapy 25 in binge eating disorder Chapter 3 Dialectical behavior therapy adapted for binge eating 57 compared to cognitive behavior therapy in obese adults with binge eating disorder: a controlled study Chapter 4 Dialectical behavior therapy compared to cognitive behavior 81 therapy in binge eating disorder: an effectiveness study with six-month follow-up Chapter 5 Dialectical behavior therapy and cognitive behavior therapy 109 in individuals with binge eating disorder: what works for whom? Chapter 6 Summary and general discussion 135 Nederlandse samenvatting [Dutch summary] 160 Curriculum vitae 166 List of publications 167 Dankwoord [acknowledgements] 169

General introduction

10 Chapter 1 General introduction Alice is a 36-year old mother of two boys, aged eight and ten years. She is married and currently on sick leave from her job as a nurse because it all felt too much for her. Ever since she was about 15 years old, she has, on and off, been suffering from episodes in which she eats a lot more than most people would eat under similar circumstances. In these episodes, she senses a lack of control over her eating, she eats without feeling hungry and eats much more rapidly than normal, until feeling uncomfortably full. After such an episode, she feels disgusted, depressed and guilty. Over the past three months she had one to seven of these binge eating episodes each week and, painfully, nobody knows. A behavioral pattern of recurrent episodes of uncontrollable overeating, in the absence of compensatory behaviors that are typical for bulimia nervosa (e.g. self-induced vomiting, using laxatives), was identified as a topic for further research three decades ago in DSM-IV (APA, 1994). In DSM-5, the provisional criteria of this ‘new’ eating disorder were refined, and included as binge eating disorder (BED) in the feeding and eating disorders section (APA, 2013: see appendix for criteria). An important distinction between BED and the two ‘classic’ eating disorders, anorexia nervosa (AN) and bulimia nervosa (BN), is that no body-image aspects (e.g. overvaluation of bodyweight and – shape in self-esteem) are incorporated in the classification. The severity of the disorder is typically specified based on the amount of uncontrollable, actual overeating (objective binge eating: OBE) episodes per week ranging from mild (1 – 3) to extreme (14 or more OBE episodes per week). BED is significantly associated with somatic comorbidity, specifically with obesity, diabetes and circulatory system diseases. Individuals with BED and obesity are more likely to report a lifetime history of respiratory and gastrointestinal diseases than those with BED without obesity. However, some diseases in individuals with BED, including components of metabolic syndrome, may not be merely due to the effects of obesity (Thornton et al., 2017). Besides somatic comorbidity, psychiatric comorbidity such as mood disorders, anxiety disorders, alcohol and drug use disorders, and personality disorders, is common in individuals with BED (Udo & Grilo, 2019; Welch et al., 2016). And, partly related to this, BED is associated with significant psychosocial and health related impairment in quality of life (Ágh et al., 2015; Striegel et al., 2012). Alice feels terribly ashamed about her body and tends to hide it from other people, including her husband. These feelings may also prevent her from going out with friends. She worries about the possible physical consequences of her overweight (she currently has a BMI of 40) and it makes her feel sad to notice that she is physically

11 General introduction 1 unable to play football with her boys. She perceives the urge to overeat especially when she feels sad or lonely, and senses that binge eating provides her with a short moment of relief. Yet, after a binge episode, Alice tells herself things like: “Oh you stupid fat pig, you did it again. You have no control, you are such an idiot! You start afresh tomorrow: skip your breakfast and stick to your diet”. Overall, she feels depressed and anxious. Currently, BED is estimated to affect 1.5% of adult women and 0.3% of adult men worldwide (Keski-Rahkonen, 2021). A lifetime diagnosis of BED is reported by 2.8% (0.6–5.8%) of women and 1.0% (0.3–2.0%) of men. This makes BED more common than AN and BN, with a lifetime prevalence of respectively 1.4% and 1.9% for women and 0.2% and 0.6% for men (Galmiche et al., 2019). Specific prevalence rates of BED among those people whose gender identity differs from the gender they were assigned at birth (transgender and gender diverse people), are so far unknown. However, based on self-report, eating disorders in general are more prevalent in this group than among people whose gender identity aligns with gender assigned at birth (cis-gender) (Diemer et al., 2015). Although relatively prevalent when compared to AN or BN, and associated with a serious clinical burden, BED tends to go undetected and untreated in the community (Coffino et al., 2019; Hudson et al., 2007). This may, at least in part, be due to the fact that individuals with BED do not fit the public image of eating disorders: a low-weight, white, young woman (Sim, 2019). For therapists and physicians in the field, this image is strengthened by the fact that eating disorder research is predominantly done in treatment-seeking individuals, where both men and ethnic minorities are substantially underrepresented (Coffino et al., 2019; National Institutes of Health, 2018). This underrepresentation may also apply to transgender and gender-diverse people as they have reported to experience various barriers in access to eating disorder screening and treatment (Ferrucci et al., 2023). Specific treatments have shown to be effective in treatment-seeking adults with BED (Linardon, Fairburn et al., 2017; Linardon, Wade et al., 2017). The strongest evidence is for cognitive behavior therapy (CBT), which is the current treatment of choice according to clinical practice guidelines (e.g. Akwa GGZ, 2017; Hay et al., 2014; NICE, 2017). Interpersonal psychotherapy (IPT) is considered a strong empirically-supported alternative (Linardon, Fairburn et al., 2017). In BED research, treatment outcome is primarily defined in terms of a decrease in or absence of eating disorder psychopathology or OBE episodes (Linardon, Fairburn et al., 2017). With CBT, up to 50% of patients reach abstinence from binge eating (Linardon, 2018). The positive effects of CBT extend to depressive symptoms (Fairburn et al., 2015; Turner et al., 2016) and to cognitive symptoms like eating concerns and

12 Chapter 1 shape/weight concerns, but no substantial weight loss is attained (Brownley et al., 2016). Concurrently, this implies that up to 50% of individuals do not fully respond to treatment. Given the physical, psychological and social burden associated with BED (Ágh et al., 2015; Thornton et al., 2017; Udo & Grilo, 2019), these data emphasize the need to improve the effectiveness of treatment. One way to improve treatment outcome is to develop new interventions that may better fit the needs and possibilities of patients. CBT is based on the transdiagnostic model of eating disorders, which implies that distinctive eating disorders are maintained by similar mechanisms (Fairburn et al., 2003). The model proposes that, in all eating disorders, self-worth is primarily defined in terms of control over body shape and weight. This shape and weight overvaluation leads to rigid rules regarding food and eating that are very difficult to maintain. Breaking a dietary rule may lead to breaking all attempts to control eating, and thus to a binge eating episode. In turn, binge eating strengthens patients’ concerns about their ability to control shape and weight, hence encouraging greater dietary restraint and increasing the risk of binge eating. Clinical perfectionism, interpersonal difficulties, low self-esteem and mood intolerance are acknowledged to act as possible co-occurring maintaining factors in many patients. However, the core CBT-protocol focusses on behavior (i.e. strict dieting) that is related to the overvaluation of body shape and weight (Fairburn, 2008). Although CBT is the first line treatment for BED, there are several issues that raise questions about whether CBT is the best suited treatment for individuals with BED. First of all, contrary to AN and BN, the central transdiagnostic concept of shape and weight overvaluation is not a defining characteristic of BED (DSM-5: APA, 2013). In addition, dietary restriction seems to be stronger in AN and BN than in BED (Elran-Barak et al., 2015; Raymond et al., 2012). And notably, evidence suggests that binge eating in obese BED individuals is not so much associated with dietary restraint (Carrard et al., 2012; Goldschmidt et al., 2011; Welsh & King, 2016), but is particularly triggered by high levels of negative affect (e.g. Haedt-Matt & Keel, 2011; Leehr et al., 2015). Eating in response to negative emotions (emotional eating) has been considered an atypical stress response, as the typical response to stress is suppressed appetite (e.g. Tsenkova et al., 2013). Emotional eating has been associated with higher levels of emotion regulation difficulties (Sultson & Akkermann, 2019) and with other affect-related problems like emotional dysregulation, poor interoceptive awareness and high alexithymia (van Strien, 2018). All in all, interventions that specifically target affect-related difficulties may likely improve outcome in individuals with BED.

13 General introduction 1 The most extensive and empirically validated affect regulation treatment to date, is dialectical behavior therapy (DBT) (Gillespie et al., 2022; Lynch et al., 2007). DBT was originally developed for patients with borderline personality disorder and ongoing self-harm or suicidal behaviors (Linehan, 1993). The treatment is built on the biosocial theory, asserting that a biological tendency toward emotional vulnerability, in combination with an invalidating rearing environment, leads to pervasive emotion dysregulation. Thus, behavioral dysregulation like self-harm, is understood as a natural reaction to environmental reinforcers (Lynch et al., 2007). In the same way, binge eating in BED can be seen as a way to regulate emotions: binge eating is triggered by high levels of negative affect and binge eating reduces negative affect (Hawkins & Clement, 1984; Telch et al., 2001). While the second part of this hypothesis has received mixed empirical support (e.g. Arnow et al., 1992; Berg et al., 2015 and Haedt-Matt & Keel, 2011), the first part has received substantial support from both experimental studies (Leehr et al., 2015), retrospective studies (e.g. Arnow et al., 1992; Vanderlinden et al., 2004), and ecological momentary assessment (EMA) studies (Berg et al., 2015; Haedt-Matt & Keel, 2011). Also, greater elevations of negative affect preceded binge eating in BED when compared to BN (Haedt-Matt & Keel, 2011). Thus, DBT has been adapted for BED (DBT-BED: Safer et al., 2009; Telch et al., 2001). DBT-BED aims to improve adaptive emotion regulation skills, so these can replace binge eating as a way of coping with negative affect. This is done from a ‘dialectical’ stance: validate patients’ current experiences and behaviors and simultaneously stimulate them to change so they can reach their goals. The adaptive skills are taught over three modules: 1) mindfulness (e.g. nonjudgmental observation and moment-to-moment awareness of emotional experiences, thoughts and action urges); 2) emotion regulation (e.g. acting opposite to one’s emotion and ‘ride the wave’ of emotions); and 3) distress tolerance (e.g. radical acceptance and self-soothing) (Safer et al., 2009). Figure 1 depicts a schematic outline of the CBT and the DBT-models of binge eating.

14 Chapter 1 Figure 1: CBT and DBT-treatment models of binge eating *: Although, in CBT, binge eating may also be maintained by negative affect, the main focus in CBT is on the link between overvaluation, dieting and binge eating. Evidence to date, comparing DBT-BED to a waitlist (e.g. Masson et al., 2013; Telch et al., 2001) and to a psychological placebo-intervention (Safer et al., 2010), supports the idea that DBT can be a valuable asset in the treatment for patients with binge eating. However, only one study directly compared DBT-BED to CBT (Chen et al., 2017). They found no differences in OBE days between treatments at the end of treatment or at follow-up in a combined BN and BED sample. To our knowledge, no study looked at DBT’s relative effectiveness in a BED-only group. Therefore, a direct comparison between CBT and DBT in individuals with BED, would fill the gap in knowledge regarding the effectiveness of DBT-BED. Also, a better understanding of what works for whom could help to better match patients to a specific treatment and thus increase treatment success. Even if two treatments do not differ in treatment outcome overall, subsets of patients, with certain symptom presentations or characteristics, may profit more from one treatment or another. This highlights the importance of identifying baseline variables that interact with treatment type to differentially predict treatment outcome (also known as moderators: Kraemer et al., 2002). To date, only a limited number of BED-studies tested moderators of manualized CBT-outcome relative to other treatments. These treatments include IPT, CBT-guided self-help (CBT-gsh), behavioral weight loss and medication (Grilo et al., 2012; Grilo, Gueorguieva & Pittman, 2021; Grilo, Thompson-Brenner et al., 2021; Linardon, de la Piedad Garcia & Brennan, 2017). Most moderators tested (e.g., demographics, global eating

15 General introduction 1 disorder psychopathology and depression scores) did not affect CBT-outcome relative to these other treatments. Some moderators (e.g. age of binge eating onset, weight concern and overvaluation of weight and shape) did differentially predict outcome in some studies, but no consistent pattern emerged across studies (Grilo, Thompson-Brenner et al., 2021; Linardon, de la Piedad Garcia & Brennan, 2017). No study so far, has tested moderators of response comparing CBT and DBT-BED. All in all, we expect that DBT-BED will lead to better outcome (i.e. more decrease in OBE episodes and in general eating disorder pathology as well as in emotion regulation difficulties) than CBT in individuals with BED in general. Also, we expect that DBT-BED will result in greater symptom improvement than CBT for patients with more distinct emotion regulation problems at baseline. Furthermore, we expect that patients with greater baseline difficulties in areas related to dieting and overvaluation of body shape and weight, and maybe also self-esteem, will show greater improvement in CBT+ compared to DBT-BED. Another way to improve treatment outcome is to explore and assess variables that predict outcome regardless of treatment type (non-specific predictors, Kraemer et al., 2002). This provides prognostic information on an individual’s likely success in treatment (Linardon, de la Piedad Garcia, & Brennan, 2017). This information can be used to positively impact clinical decision making and thereby augment successful outcomes. Past studies have explored a broad range of predictors of BED treatment outcome. For instance, higher levels of eating disorder pathology at baseline (such as binge eating frequency, global eating disorder psychopathology and shape and weight concern) have been associated with more eating disorder pathology at end of treatment (EOT) and follow-up (FU) (Castellini et al., 2011; Grilo et al., 2012; Hilbert et al., 2007; Masheb & Grilo, 2008; Thompson-Brenner et al., 2013). Also, DSM-IV Axis I and II comorbidity has been associated with worse treatment outcome (Castellini et al., 2011; Fichter et al., 2008; Masheb & Grilo, 2008; Wilson et al., 2010). Others on the other hand, find no predictive value for any Axis I or II disorder (Grilo et al., 2012; Ricca et al., 2010). Taken together, the body of research is fragmented and findings are partly inconsistent (Linardon, de la Piedad Garcia & Brennan, 2017). Therefore, more research is needed. Aims and outline of this thesis The aim of this thesis is to improve the effectiveness of treatment for individuals with BED by identifying variables that predict outcome regardless of treatment type and, most importantly, by exploring the potential added value of an alternative treatment, i.e. DBT-BED, to the current first line treatment, CBT.

16 Chapter 1 We will address the following questions: · Which variables predict outcome regardless of treatment type, in treatment seeking individuals with (subthreshold) BED? (Chapters 2 and 5) · What is the effectiveness of DBT-BED compared to an intensive outpatient group CBT-program (CBT+) in a group of individuals with BED who may arguably profit most from an emotion regulation focused intervention? (Chapter 3) · What is the effectiveness of DBT-BED compared to CBT+ in a broader group of individuals with (subthreshold) BED in everyday clinical practice? (Chapter 4) · Which patients profit most from CBT+ and which patients may be more likely to profit from DBT-BED? (Chapter 5) Chapter 6 provides a summary and general discussion of the main findings. Moreover, strengths and limitations are considered, and recommendations for future research and clinical practice are made.

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20 Chapter 1 Kraemer, H. C., Wilson, G. T., Fairburn, C. G., & Agras, W. S. (2002). Mediators and moderators of treatment effects in randomized clinical trials. Archives of General Psychiatry, 59, 877–883. 10.1001/archpsyc.59.10.877. Leehr, E. J., Krohmer, K., Schag, K., Dresler, T., Zipfel, S., & Giel, K. E. (2015). Emotion regulation model in binge eating disorder and obesity: A systematic review. Neuroscience & Biobehavioral Reviews, 49, 125–134. Linardon J. (2018). Rates of abstinence following psychological or behavioral treatments for binge-eating disorder: Meta-analysis. International Journal of Eating Disorders, 51, 785–797. Linardon, J., de la Piedad Garcia, X., & Brennan, L. (2017). Predictors, moderators, and mediators of treatment outcome following manualized cognitive-behavioural therapy for eating disorders: A systematic review. European Eating Disorders Review, 25, 3–12. https://doi.org/10.1002/erv.2492 Linardon, J., Fairburn, C. G., Fitzsimmons-Craft, E. E., Wilfley, D. E., & Brennan, L. (2017). The empirical status of the third-wave behaviour therapies for the treatment of eating disorders: A systematic review. Clinical Psychology Review, 58, 125–140. https:// doi.org/10.1016/j.cpr.2017.10.005 Linardon, J., Wade, T. D., de la Piedad Garcia, X., & Brennan, L. (2017). The efficacy of cognitive-behavioral therapy for eating disorders: A systematic review and metaanalysis. Journal of Consulting and Clinical Psychology, 85, 1080–1094. http://dx.doi. org/10.1037/ccp0000245 Linehan, M. M. (1993). Cognitive behavioral therapy of borderline personality disorder. Guilford Press. Lynch, T. R., Trost, W. T., Salsman, N., Linehan, M. M. (2007). Dialectical behavior therapy for borderline personality disorder. Annual Review of Clinical Psychology, 3, 181-205. https://doi.org/10.1146/annurev.clinpsy.2.022305.095229 Masheb, R. M., & Grilo, C. M. (2008). Examination of predictors and moderators for self-help treatments of binge-eating disorder. Journal of Consulting and Clinical Psychology, 76, 900–904. DOI:10.1037/a0012917. Masson, P. C., von Ranson, K. M., Wallace, L. M., & Safer, D. L. (2013). A randomized waitlist controlled pilot study of dialectical behaviour therapy guided self-help for binge eating disorder. Behaviour Research and Therapy, 51, 723–728. National Institutes of Health [NIH] (n.d.). NIH RCDC inclusion statistics report. Retrieved January 13, 2023, from. https://report.nih.gov/RISR/#/.

21 General introduction 1 National Institute for Health and Care Excellence [NICE] (2017). Eating disorders: Recognition and treatment. https://www.nice.org.uk/guidance/ng69/chapter/ Recommendations#treating-binge-eating-disorder Raymond, N. C., Peterson, R. E., Bartholome, L. T., Raatz, S. K., Jensen, M. D., & Levine, J. A. (2012). Comparisons of energy intake and energy expenditure in overweight and obese women with and without binge eating disorder. Obesity, 20, 765–772. Ricca, V., Castellini, G., Mannucci, E., Lo Sauro, C., Ravaldi, C., Rotella, C. M., & Faravelli, C. (2010). Comparison of individual and group cognitive behavioral therapy for binge eating disorder. A randomized, three-year follow-up study. Appetite, 55, 656–665. 10.1001/archpsyc.59.8.713. Safer, D. L., Robinson, A. H., & Jo, B. (2010). Outcome from a randomized controlled trial of group therapy for binge eating disorder: Comparing dialectical behavior therapy adapted for binge eating to an active comparison group therapy. Behavior Therapy, 41, 106–120. Safer, D. L., Telch, C. F., & Chen, E. Y. (2009). Dialectical behavior therapy for binge eating and bulimia. Guilford Press. Sim, L. (2019). Our eating disorders blind spot: Sex and ethnic/racial disparities in helpseeking for eating disorders. Mayo Clinic Proceedings, 94, 1398-1400. https://doi. org/10.1016/j.mayocp.2019.06.006, Striegel, R., Bedrosian, R., Wang, C., & Schwartz, S. (2012). Why men should be included in research on binge eating: Results from a comparison of psychosocial impairment in men and women. International Journal of Eating Disorders, 45, 233–240. DOI: 10.1002/ eat.20962 Sultson, H., & Akkermann, K. (2019). Investigating phenotypes of emotional eating based on weight categories: A latent profile analysis. International Journal of Eating Disorders, 52, 1024–1034. Telch, C. F., Agras, W. S., & Linehan, M. M. (2001). Dialectical behavior therapy for binge eating disorder. Journal of Consulting and Clinical Psychology, 69, 1061–1065. Thompson-Brenner, H., Franko, D. L., Thompson, D. R., Grilo, C. M., Boisseau, C. L., Roehrig, J. P., Richards, L. K., Bryson, S. W., Bulik, C. M., Crow, S. J., Devlin, M. J., Gorin, A. A., Kristeller, J. L., Masheb, R., Mitchell, J. E., Peterson, C. B., Safer, D. L., Striegel, R. H., Wilfley, D. E., & Wilson, G. T. (2013). Race/ethnicity, and treatment parameters as moderators and predictors of outcome in binge eating disorder. Journal of Consulting and Clinical Psychology, 81, 710–721. DOI:10.1037/a0032946.

22 Chapter 1 Thornton, L. M., Watson, H. J., Jangmo, A., Welch, E., Wiklund, C., von Hausswolff Juhlin, Y., Norring, C., Herman, B. K., Larsson, H., & Bulik, C. M. (2017). Binge-eating disorder in the Swedish national registers: Somatic comorbidity. International Journal of Eating Disorders, 50, 58–65. DOI10.1002/eat.22624 Tsenkova, V., Morozink Boylan, J., & Ryff, C. (2013). Stress eating and health: Findings from MIDUS, a National Study of U.S. Adults, Appetite, 69, 151–155. doi:0.1016/j. appet.2013.05.020 Turner, H., Marshall, E., Wood, F., Stopa, L., & Waller, G. (2016). CBT for eating disorders: The impact of early changes in eating pathology on later changes in personality pathology, anxiety and depression. Behaviour Research and Therapy, 77, 1-6. Udo, T., & Grilo, C. M. (2019). Psychiatric and medical correlates of DSM-5 eating disorders in a nationally representative sample of adults in the United States. International Journal of Eating Disorders, 52, 42–50. DOI: 10.1002/eat.23004 Van Strien (2018). Causes of emotional eating and matched treatment of obesity. Current Diabetes Reports, 18, 35. https://doi.org/10.1007/s11892-018-1000Vanderlinden, J., Grave, R. D., Fernandez, F., Vandereycken, W., Pieters, G., & Noorduin, C. (2004). Which factors do provoke binge eating? An exploratory study in eating disorder patients. Eating and Weight Disorders, 9, 300–305. Welch, E., Jangmo, A., Thornton, L. M., Norring, C., von Hausswolff-Juhlin, Y., Herman, B. K., Pawaskar, M., Larsson, H., & Bulik, C. M. (2016). Treatment-seeking patients with binge eating disorder in the Swedish national registers: clinical course and psychiatric comorbidity. BMC Psychiatry, 16, 163. DOI 10.1186/s12888-016-0840-7 Welsh, D. M., & King, R. M. (2016). Applicability of the dual pathway model in normal and overweight binge eaters. Body Image, 18, 162–167. Wilson, G. T., Wilfley, D. E., Agras, W. S., & Bryson, S. W. (2010). Psychological treatments of binge eating disorder. Archives of General Psychiatry, 67, 94–101. DOI:10.1001/ archgenpsychiatry. 2009.170.

23 General introduction 1 Appendix Diagnostic criteria for binge eating disorder DSM-5 (American Psychiatric Association, 2013). A. Recurrent episodes of binge eating. An episode of binge eating is characterized by both of the following: 1. Eating, in a discrete period of time (e.g. within any 2-hour period), an amount of food that is definitely larger than what most people would eat in a similar period of time under similar circumstances. 2. A sense of lack of control over eating during the episode (e.g. a feeling that one cannot stop eating or control what one is eating). B. The binge eating episodes are associated with three (or more) of the following: 1. Eating much more rapidly than normal; 2. Eating until feeling uncomfortably full; 3. Eating large amounts of food when not feeling physically hungry; 4. Eating alone because of feeling embarrassed by how much one is eating; 5. Feeling disgusted with oneself, depressed, or very guilty afterwards. C. Marked distress regarding binge eating is present. D. The binge eating occurs, on average, at least once a week for 3 months. E. The binge eating is not associated with the recurrent use of inappropriate compensatory behaviours as in bulimia nervosa and does not occur exclusively during the course of bulimia nervosa or anorexia nervosa. Specify current severity: Mild: 1-3 binge eating episodes per week Moderate: 4-7 binge eating episodes per week Severe: 8-13 binge eating episodes per week Extreme: 14 or more binge eating episodes per week

Published as: Lammers, M. W., Vroling, M. S., Ouwens, M. A., Engels, C. M. E., & van Strien, T. (2015). Predictors of outcome for cognitive behaviour therapy in binge eating disorder. European Eating Disorders Review, 23, 219-228. DOI: 10.1002/erv.2356

Predictors of outcome for cognitive behaviour therapy in binge eating disorder

26 Chapter 2 Abstract The aim of this naturalistic study was to identify pretreatment predictors of response to cognitive behaviour therapy in treatment-seeking patients with binge eating disorder (BED) (N = 304). Furthermore, we examined end-of-treatment factors that predict treatment outcome six months later (N = 190). We assessed eating disorder psychopathology, general psychopathology, personality characteristics and demographic variables using self-report questionnaires. Treatment outcome was measured using the bulimia subscale of the Eating Disorder Inventory 1. Predictors were determined using hierarchical linear regression analyses. Several variables significantly predicted outcome, four of which were found to be both baseline predictors of treatment outcome and end-of-treatment predictors of follow-up: Higher levels of drive for thinness, higher levels of interoceptive awareness, lower levels of binge eating pathology and, in women, lower levels of body dissatisfaction predicted better outcome in the short and longer term. Based on these results, several suggestions are made to improve treatment outcome for BED patients. Keywords Binge eating disorder; cognitive behaviour therapy; treatment outcome; predictors

27 Predictors of outcome for cognitive behaviour therapy in binge eating disorder 2 Introduction Binge eating disorder (BED) is characterised by recurrent episodes of uncontrollable overeating without the use of regular, inappropriate compensatory behaviours that are typical for bulimia nervosa (APA, 1994; 2013). Prevalence rates, based on DSM-IV criteria, vary across studies, ranging from 1% to 6.6% in the general population (Grucza et al., 2007; Hoek & Van Hoeken, 2003; Preti, et al., 2009). Among people applying for weight loss treatment prevalence rates are as high as 30% (Niego et al., 2007; Spitzer et al., 1993). BED is frequently associated with obesity. About 70% of BED patients suffer from obesity with a body mass index (BMI) between 30 and 40, whereas about 20% suffer from morbid obesity with a BMI equal to or over 40 (Grucza et al., 2007). Although BED and obesity are associated, individuals with BED differ distinctively from obese people who do not binge. For instance, they report higher calorie intake in non-binge meals, more concerns about shape and weight, more psychiatric problems and lower overall quality of life than obese people without BED (Ahrberg et al., 2011; Grucza et al., 2007; Rieger et al., 2005; Telch & Stice, 1998; Wilfley et al., 2003; Yanovski et al., 1993). Interpersonal psychotherapy (IPT), dialectical behaviour therapy (DBT) and cognitive behaviour therapy (CBT) have all been shown to reduce binge eating substantially, with the latter currently being the treatment of choice for BED (NICE, 2004; Yager, et al., 2012). Abstinence rates for CBT vary across studies and range from 17% to 79% of patients at post-treatment, from 21% to 59% 1 year after treatment and were found to be 36% 3 years after treatment (Grilo et al., 2011; Peterson et al., 2009; Ricca et al., 2010; Wilfley et al., 2002). The positive effects of CBT extend to overconcern with eating, weight and shape and to psychosocial functioning, but CBT does not lead to substantial weight loss (Brownley et al, 2007; Vocks et al, 2010; Wilson et al., 2010; Wilson et al., 2007). Considering the fact that a substantial number of patients do not reach abstinence from binge eating, it is important to establish predictors of treatment response, as this may lead to more targeted and effective interventions. Throughout the years, research on predictors of outcome for BED treatment has focussed on the domains of eating disorder pathology, clinical characteristics and demographic variables. Several recent findings on predictors related to eating disorder pathology indicate that higher baseline levels of both self-reported binge eating frequency and eating disorder psychopathology, as conceptualised by the global Eating Disorder Examination (Questionnaire) score, predict more eating disorder pathology at post-treatment and at longer-term follow-up (Castellini et al., 2011; Grilo et al., 012; Masheb & Grilo, 2008; Thompson-Brenner et al., 2013). However, binge eating frequency at baseline does not predict a diagnostic full recovery (Ricca et al., 2010). In addition, a higher baseline level of body dissatisfaction (i.e. shape and weight concerns) predicts less

28 Chapter 2 remission from binge eating after treatment (Grilo et al., 2012; Hilbert et al., 2007) and higher pretreatment levels of body dissatisfaction predict BED outcome at the 12-year follow-up (Fichter et al., 2008). The reduction of eating disorder-related pathology to within the normal range at post-treatment is the best predictor of recovery at follow up (Lock et al., 2013). Some evidence suggests that other predictors related to eating disorder pathology, such as high baseline levels of emotional eating and BMI, predict a poorer treatment outcome (Fichter et al., 2008; Ricca et al., 2010; Thompson-Brenner et al., 2013). The difference between one’s current body weight and highest adult body weight, however, is not predictive of percentage reduction in binge eating episodes nor does it predict abstinence from binge eating (Zunker et al. 2011). Some research on predictors related to clinical characteristics suggests that lower self-esteem and more interpersonal problems at baseline predict more eating disorder pathology at post-treatment (Hilbert et al., 2007; Wilson et al., 2010). Whereas some studies suggest that depression levels predict remission from binge eating (Wilson et al., 2010) and that more negative affect leads to more eating disorder psychopathology (Masheb & Grilo, 2008), other studies do not show such a relationship (Grilo et al, 2012; Ricca et al., 2010). Furthermore, data on concomitant Axis I and II classifications are mixed. In some studies, comorbidity on Axis I (i.e. depression) was found to be a predictor for less remission of binge eating in the longer term (Castellini et al., 2011; Fichter et al., 2008; Wilson et al., 2010) and the presence of personality disorders, particularly cluster C, predicted more post-treatment eating disorder psychopathology (Masheb & Grilo, 2008). In other studies however, no predictive value was found for any Axis I or II disorder (Grilo et al., 2012; Ricca et al., 2010). The evidence on predictors related to demographic variables is also mixed. Older age of BED onset predicted less eating disorder pathology (i.e. remission from binge eating) at post-treatment in one study, but not in another (Grilo et al., 2012 and Masheb & Grilo, 2008, respectively). Age at presentation for treatment did not predict levels of eating pathology at post-treatment in one study (Masheb & Grilo, 2008), whereas in another study, older age at presentation for treatment predicted greater reduction in objective bulimic episodes and greater rates of cessation of objective bulimic episodes (ThompsonBrenner et al., 2013). When looking at the long term, lower age was associated with full recovery (Castellini et al., 2011). Additionally, in one study, BED patients with less than a college education were more likely to remit from binge eating at post-treatment than patients with a higher education (Grilo et al., 2012). However, when looking at aggregated data of 11 studies, a lower level of education (less than high school) predicted more objective bulimic episodes at post-treatment (Thompson-Brenner et al., 2013).

29 Predictors of outcome for cognitive behaviour therapy in binge eating disorder 2 All things considered, the body of recent research on predictors of treatment outcome for BED is limited and partly contradictory. A possible explanation for the mixed findings is the relatively small sample size used in most studies. In addition, studies tend to combine data from different interventions such as guided self-help, behavioural weight loss, CBT group therapy and individual IPT for predictor-of-outcome analyses (Masheb & Grilo, 2008; Ricca et al., 2010; Wilson et al., 2010; Zunker et al., 2011). Only a few studies report on the longer-term efficacy of treatment (Castellini et al., 2011; Fichter et al., 2008; Hilbert et al., 2007; Ricca et al, 2010; Wilson et al., 2010; Zunker et al., 2011) and only one study examined the predictive value of end-of-treatment outcomes for longer-term recovery status in BED (Lock et al., 2013). Additionally, the focus of most studies is on methodologically sound but ecologically less valid randomised controlled trials (RCTs). Applied exclusion criteria in RCTs include medical conditions that might influence eating or weight (such as diabetes) and the use of psychotropic medication (such as antidepressants) (Grilo et al., 2012; Hilbert et al., 2007; Masheb & Grilo, 2008; Ricca et al., 2010; Wilson et al., 2010). However, obese BED patients are known to suffer from depression and diabetes (Finkelstein et al., 2007; Grilo et al, 2009; Telch & Stice, 1998). A naturalistic design could take these patient groups into account. To our knowledge, only three naturalistic treatment intervention studies have been conducted, with two of these using a large sample size (Castellini et al., 2011; Deumens et al., 2012; Fichter et al., 2008). The study by Deumens et al. (2012) was conducted at our treatment centre. They examined pretreatment predictors of post-treatment outcome, using a composite score of the subscales drive for thinness, bulimia and interoceptive awareness of the Eating Disorder Inventory (EDI)-I as outcome measure in 182 BED patients. They found that being in a romantic relationship and/or living with one’s parents (‘high social embedding’) and more openness to experience predicted more improvement at post-treatment. In addition, more depressive symptoms, more agoraphobia and more extraversion were significantly related to less improvement after treatment. The present study builds on the study by Deumens et al. (2012) using partially the same population. This study, however, differs from the one by Deumens and colleagues by its use of a larger patient sample (N = 304 completers), the inclusion of follow-up measures 6 months after treatment and its use of a more specific operationalisation of binge eating pathology as outcome measure (EDI bulimia scale scores instead of the composite score used by Deumens et al.). Specifically, we investigated what factors predict who will benefit from treatment in terms of binge eating pathology and what factors at end of treatment predict outcome at follow-up. In searching for these predictors, we focussed on group CBT for BED in an intensive outpatient treatment environment. Potential predictors were chosen to study seemingly unequivocal findings (levels of eating disorder pathology, body dissatisfaction, BMI and education) and to study less unequivocal findings (level of psychopathology, personality characteristics, age and social embedding).

30 Chapter 2 Method Participants Participants were 431 patients (399 women, 32 men), who met DSM-IV (APA, 1994) research criteria for BED. They were all referred to Amarum, a specialist centre for the treatment of eating disorders in the Netherlands1, by their general practitioner or another clinician. Information about the diagnosis was gathered through different channels. An initial screening on eating disorder complaints was conducted by telephone. Next, patients filled out a personal history questionnaire including questions about eating disorder-related behaviour and psychiatric comorbidity. If applicable, information about former treatments was retrieved. Subsequently, a clinical interview by either a licensed psychologist or a psychiatrist was conducted in which, among other things, the presence of BED was determined and a case formulation was phrased. The case formulation as well as the DSM-IV classification were then reviewed in a multidisciplinary team. Exclusion criteria for participating in the treatment programme were concurrent treatment for binge eating disorder or weight problems (yet those who have undergone bariatric surgery can be included); comorbid psychiatric conditions that warrant immediate attention (e.g., suicidality, acute psychosis); medical conditions that preclude outpatient treatment; conditions that preclude participation in group treatment (e.g. mental retardation); pregnancy; age below 18 or above 65. All participants started treatment between September 2003 and April 2011 and provided written informed consent. Of these 431 patients, 341 patients (316 women and 25 men) completed their treatment programme. A total of 90 patients dropped out of treatment (83 women and 7 men). Reasons for dropping out were the patient’s unilateral belief that he/she had improved sufficiently, or in accordance with advice from the therapist because the therapist had doubts about the patient’s resilience or because a co morbid disorder required attention first. For some patients, reasons were unknown. Of the 341 patients who completed treatment, 304 completed the post-treatment measurement (these patients will be used for post-treatment prediction), and 190 completed the 6-month follow-up measurement (these patients will be used for follow-up prediction). Of the 304 patients that completed both treatment and measures at post-treatment, mean age at pretreatment was 36.38 (SD = 9.35, range 18 – 60). Mean pretreatment BMI 1 Treatment is offered either in Zutphen or in Nijmegen.

31 Predictors of outcome for cognitive behaviour therapy in binge eating disorder 2 was 41.92 kg/m2 (SD = 6.90, range 25 – 66 kg/m2). Of these patients, 2.0% were overweight (BMI 25 - 29.9 kg/m2), 12.2 % were Grade I obese (BMI 30 – 34.9 kg/m2), 30.4% were Grade II obese (BMI 35 – 39.9 kg/m2), and 55.4% were morbidly obese (BMI 40 kg/m2 and higher). Age and BMI distribution for treatment-completing patients that completed follow-up measures were similar to those reported earlier. Materials Eating disorder-related measures The Dutch translation of the EDI-1 was used as a measure for eating disorder psychopathology (Garner et al., 1983; Schoemaker et al., 1994). The EDI-1 consists of 64 items concerning psychological and behavioural eating disorder symptomatology. Items such as ‘I feel extremely guilty after overeating’ are answered on a 6-point Likert scale. The EDI-1 consists of eight subscales: drive for thinness (DT), bulimia, (B), body dissatisfaction (BD), ineffectiveness (I), perfectionism (P), interpersonal distrust (ID), interoceptive awareness (IA), and maturity fears (MF). Higher scores indicate higher eating disorder psychopathology. The bulimia subscale was used as the measure for binge eating pathology. The reliability and the validity are considered to be good for use in eating disorder patient groups (e.g., Garner et al., 1983; Van Strien & Ouwens, 2003; Welch et al., 1990), and internal consistency was found to be good in the present sample (α = .805). The Dutch version of the Body Attitude Test (BAT) was used to measure subjective body experience and attitude towards one’s body (Probst et al., 1995). The BAT consists of 20 items such as ‘When I compare myself with my peers’ bodies, I’m dissatisfied with my own’ which are answered on a 6-point Likert scale. The BAT consists of three subscales: negative appreciation of body size, lack of familiarity with one’s own body, and general body dissatisfaction (and a rest factor). Higher scores indicate a more deviant body experience. The reliability and validity of the BAT are considered to be good (Probst et al., 2008; Probst et al., 1995), and internal consistency was found to be good in the present sample (α = .755). General psychopathology The Dutch version of the Symptom Checklist 90 (SCL-90) was used to measure general psychopathology (Arrindell & Ettema, 2003). The SCL-90 consists of 90 items related to the frequency of experienced physical (e.g., suffering from headache) and psychological (e.g., feeling lonely) complaints in the last week, which are answered on a 5-point Likert scale. The SCL-90 comprises eight subscales: agoraphobia, anxiety, depression, somatization, insufficiency, distrust, hostility and sleeplessness. The items can be summed for a total

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