Psychotherapy Outcome for Eating Disorders: a Meta-Analysis
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Psychotherapy Outcome for Eating Disorders: A Meta-Analysis Julia B. Hubbard A dissertation submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Scott Baldwin, Chair Mikle South Gary Burlingame Patrick Steffen Alan Hawkins Department of Clinical Psychology Brigham Young University June 2013 Copyright © 2013 Julia Hubbard All Rights Reserved ABSTRACT Psychotherapy Outcome for Eating Disorders: A Meta-Analysis Julia Hubbard Department of Psychology, BYU Doctor of Philosophy The purpose of this project was to summarize psychotherapy outcomes for eating disorders using meta-analysis. Psychotherapy was defined as any psychosocial treatment including face-to-face therapy, self-help, and Internet approaches. All primary studies, meeting inclusion/exclusion criteria from 1980 to 2010, were included. Results suggested that individuals treated with active treatments demonstrate better outcomes than those in control conditions ( d = 0.33, p < .01, 95% CI [0.19-0.46]). CBT was the most often occurring treatment in the primary studies and a small effect, favoring CBT, was found when the treatment was compared to all other active treatments ( d = 0.16, p = .02, 95% CI [0.03-0.28]). Internet and self-help approaches continue to show promise with Internet treatments demonstrating superior outcomes to control conditions ( d = 0.54, p < .01, 95% CI [0.19-0.90]). More research is needed to determine whether these approaches can suffice as stand-alone treatments or if they are best used in addition to already well-established approaches (i.e., individual CBT). The meta-analysis also explored whether treatment type, outcome measure, diagnosis, attrition, and diagnostic severity moderate treatment effect. Finally, the meta-analysis updated and improved upon previous meta- analyses by focusing on randomized controlled trials, including all diagnoses of eating disorder, only combining effect sizes from similar conditions, including all possible studies that meet inclusion criteria, computing and comparing effect sizes for outcome measures beyond those considered primary to eating disorder treatment, and also addressing outcomes for all brands of psychotherapy including traditional talk therapy, self-help, and Internet approaches. Keywords: eating disorders, psychotherapy outcome, meta-analysis ACKNOWLEDGEMENTS I consider life a journey on which I am continuously moving, learning, and growing. I was blessed to have many people impact and shape me on my graduate school journey. I would like to thank Dr. Scott Baldwin for his support and guidance throughout my entire graduate school career and especially during the process of completing my dissertation. His mentorship aided my confidence in and understanding of statistics, the refinement of my writing skills, and my development as a professional. I would like to acknowledge each of my committee members, Drs. Gary Burlingame, Diane Spangler, Mikle South, Patrick Steffen, and Alan Hawkins, for their feedback, encouragement, and support. I am forever grateful to Sterling Brown and Darrell Kelly for the help they provided me during the literature search and coding process. Throughout life’s journey, you never know whom you might meet or who might leave a special mark on your life. I was fortunate to develop lasting friendships with Sarah Christian, Sasha Mondragon, and Ashley Levan. Rachelle Wardle who was like a sister and accepted me as an “honorary” member of her family. Each of these individuals was irreplaceable and an inspiration to me throughout the program. Lastly, I must thank my family. As any family, we have been through so much together but I would not be who I am today without their love, encouragement, and guidance. My mother who never lets me quit without first trying, my father who has always taught me the day I think I know everything will be the day I stop learning, my brother who is truly my rock and strength who lives his life quietly but his example is louder than any words could ever be, and my sister who has a heart of gold, has always looked up to me, and believed I would never achieve less than my dreams—Thanks for loving me, no matter the distance and through my imperfections. I am eternally grateful and have more love for each of you than you could ever know. iv Table of Contents Abstract ........................................................................................................................................... ii Introduction ..................................................................................................................................... 1 Overview of Eating Disorders ......................................................................................................... 2 Anorexia Nervosa ........................................................................................................................ 2 Bulimia Nervosa .......................................................................................................................... 3 Eating Disorder Not Otherwise Specified ................................................................................... 3 Theories and Approaches of Treatment .......................................................................................... 4 Face-to-face Therapy ................................................................................................................... 4 Non-face-to-face Treatments ....................................................................................................... 9 Past Reviews of Eating Disorder Treatments ................................................................................ 11 National Institute for Clinical Excellence (NICE) .................................................................... 11 Other Meta-Analytic Work ........................................................................................................ 12 Limitations of Previous Meta-Analyses .................................................................................... 15 Current Meta-Analysis .............................................................................................................. 18 Aims of Current Meta-analysis ..................................................................................................... 19 Hypotheses .................................................................................................................................... 19 Methods ......................................................................................................................................... 20 Selection of Studies ................................................................................................................... 20 Codes ......................................................................................................................................... 21 Effect Size Calculation .............................................................................................................. 23 Inter-rater Reliability ................................................................................................................. 23 Analysis ..................................................................................................................................... 24 v Results ........................................................................................................................................... 26 Sample Characteristics .............................................................................................................. 26 Aggregate Effects ...................................................................................................................... 28 Publication Bias ......................................................................................................................... 41 Moderator Effects: Univariate Analyses ................................................................................... 45 Moderator Effects: Multivariate Analyses ................................................................................ 49 Discussion ...................................................................................................................................... 57 Overall Effects ........................................................................................................................... 57 Is CBT the Treatment of Choice? .............................................................................................. 61 Format of Treatment .................................................................................................................. 62 Internet Therapy and Self-help Treatments ............................................................................... 64 A Transdiagnostic Approach ..................................................................................................... 66 When Another Treatment has Failed ......................................................................................... 67 Limitations ................................................................................................................................. 67 Future Research ......................................................................................................................... 69 References ....................................................................................................................................