by Michael D. Anestis, M.S.
I hope everyone enjoyed their Thanksgiving holiday. We certainly enjoyed our time off, but are excited to return to PBB. Given the amount of time I spent thinking about food during this past week, with mashed potatoes playing a particularly prominent role in my thoughts, I figured it might make sense to keep food at the center of today's discussion.
In the current issue of the International Journal of Eating Disorders, a number of prominent researchers published articles discussing proposed changes for eating disorder diagnoses in the upcoming DSM-V. Several articles discussed the potential inclusion of binge eating disorder in the main text of the DSM (it is currently listed as a disorder in need of further research and results in a diagnosis of eating disorder not otherwise specified) and the addition of purging disorder and night eating syndrome as well. The article that interested me the most, however, was written by Timothy Walsh and Robyn Sysko (2009) of Columbia University and discussed a proposed overhaul of the eating disorder diagnostic system for DSM-V.
Before explaining their proposed system, Walsh and Sysko (2009) took care to explain why they believe such changes are necessary. As it stands, the DSM formally recognizes two eating disorder diagnoses: bulimia nervosa (BN) and anorexia nervosa (AN). As I mentioned above, binge eating disorder (BED) is listed in the appendix as a disorder in need of further research, so no formal BED diagnoses exists. Instead, individuals who meet criteria for BED receive a diagnosis of eating disorder not otherwise specified (EDNOS). At first glance, this might not seem all that problematic, but there are a number of other issues that clarify why this needs to be addressed. Research has demonstrated that between 50% and 70% of eating disorder diagnoses are EDNOS (Ricca et al., 2001; Turner & Bryant Waugh, 2004). In other words, the majority of individuals with an eating disorder do not meet criteria for one of the two eating disorders recognized by the DSM. As such, the catch-all residual category of EDNOS accounts for an absurdly large proportion of patients.
The problems of EDNOS are not limited to the fact that it accounts for such a high percentage of eating disorder diagnoses, however. Perhaps even more problematic than that is the fact that the category itself is so broad. Walsh and Sysko (2009) pointed out that a 14-year-old girl who meets all of the criteria for AN except that she reports menstrual activity and a 46-year-old man with BED would both be given a diagnosis of EDNOS despite the fact that these two individuals have very little in common. In other words, knowing that somebody has EDNOS tells us very little about who they are and what symptoms are causing them distress and/or impairment and yet this diagnosis is nonetheless what we are most likely to see listed in the case file for a patient with an eating disorder diagnosis.
Walsh and Sysko (2009) were thus determined to develop a diagnostic system for eating disorders that would result in substantially fewer individuals being given an EDNOS diagnosis but which would not reduce the validity of the diagnoses or cause a disconnect between current research and the new diagnoses. Their proposed model, which they named the Broad Categories for the Diagnosis of Eating Disorders (BCD-ED) involves three hierarchical categories mirroring the current most researched eating disorder diagnoses and also retains a much more limited EDNOS category. They defined the categories as follows (pg.755):
************
Anorexia Nervosa and Behaviorally Similar Disorders (AN-BSD)
"An eating disorder category characterized by the restriction of food intake relative to caloric requirements resulting in the maintenance of an inappropriately low weight, not better explained by a general medical condition or another psychiatric disorder. The prototype for this category is an individual meeting DSM-IV criteria for AN."
Bulimia Nervosa and Behaviorally Similar Disorders (BN-BSD)
"An eating disorder category characterized by recurrent out of control eating and the recurrent use of inappropriate purging methods to control eating or weight. The prototype for this category is an individual meeting DSM-IV criteria for BN."
Binge Eating Disorder and Behaviorally Similar Disorders (BED-BSD)
"An eating disorder characterized by recurrent episodes of out of control eating. The prototype for this category is an individual meeting DSM-IV criteria for BED."
Eating Disorder Not Otherwise Specified (EDNOS)
"A residual diagnostic category for all other individuals with a clinically significant eating disorder."
*************
So, Walsh and Sysko's (2009) model essentially involves shifting BED from the appendix to the main text of the DSM and including sub-threshold patients in the broader eating disorder categories rather than giving them an EDNOS diagnosis. In other words, an individual meeting all the criteria for AN except that she reports menstrual activity would now receive an AN-BSD diagnosis instead of EDNOS and an individual who frequently binge eats and purges, but averages less than twice per week would receive a diagnosis of BN-BSD rather than EDNOS.
Without question, this would result in a smaller proportion of eating disorder patients receiving EDNOS diagnoses, but the authors acknowledged two other issues that require attention. First, does the hierarchical structure of their model make sense? And second, would this shift result in an over-diagnosis of eating disorders because it is so broad?
The first question, which essentially asks whether AN is more severe than BN and whether BN is more severe than BED, is difficult to answer. For one thing, the authors could find not studies that specifically addressed that particular question. Secondly, it would be difficult to determine the relative danger of mild AN compared to severe BN, particularly if we are not also considering comorbid diagnoses, prior history of suicidal behavior, and prior responses to treatments. The authors openly admitted that this is a bit of a blurry issue; however, they also provided some evidence supporting their decision to structure the model in this manner. For one thing, of all the eating disorder classifications, AN involves the highest mortality (Hoek, 2006) and medical complication (Mitchell & Crow, 2006) rates and also the poorest treatment response and greatest rate of relapse. The picture is a bit less clear with respect to BN and BED, with some studies indicating that BN is more severe with respect to prognosis (Fairburn, Cooper, Doll, Norman, & O'Connor, 2000; Hay & Fairburn, 1998) and others not supporting any difference between the categories (Fitcher Quadfleig, & Hedlund, 2008). So, support for listing AN-BSD as the most severe is fairly strong, but support for the hierarchical structure of BN-BSD and BED-BSD is less compelling.
The second question - whether this new system would result in the over-diagnosis of eating disorders - is equally difficult to answer, as there is no way to conclusively predict the future. On the one hand, the broad nature of the categories might cause some clinicians to give a diagnosis they otherwise might not give. On the other hand, these new categories do not seem any more broad than the standard EDNOS diagnosis, so I am not certain I see any reason to believe there would be a sudden surge in diagnoses unless clinicians are simply wary of diagnosing EDNOS but somehow more willing to provide an questionable diagnosis of another eating disorder (and there are no data I am aware of that indicate this is the case). Regardless, Walsh and Sysko (2009) proposed that, in an effort to prevent over-diagnosis, the DSM-V should include specific criteria requiring functional impairment as a direct result of disordered eating. In other words, the DSM-V should be clear about what constitutes clinically significant distress and/or impairment so as to help clinicians determine if a particular patient warrants a diagnosis (e.g., does the client exhibit an "inappropriately low" weight? Does the client binge eat often enough?).
On the whole, I think that this model is imperfect, but a great idea. Reducing the reliance upon EDNOS is an important goal for DSM-V. I do, however, have a couple of concerns that went unaddressed in the Walsh and Sysko (2009) article. First, in their definition of BN-BSD, they mentioned that the client must exhibit "purging" behaviors whereas DSM-IV requires "inappropriate compensatory behaviors." Purging involves attempts to immediately expel what was previously consumed (e.g., self-induced vomiting, the use of laxatives) whereas the broader category of compensatory behaviors can include non-purging behaviors aimed at weight control such as excessive exercising and fasting. Does the Walsh and Sysko (2009) model thus require a reclassification of some individuals who would otherwise meet criteria for BN and, if so, is such a change justified (e.g., do individuals with purging versus non-purging BN respond differently to different treatments?)? Additionally, the new model does not address the issue of purging disorder. Night eating syndrome seems likely to end up in the BED-BSD category, but purging disorder seems likely to still result in an EDNOS diagnosis. It might be that Walsh and Sysko (2009) want to see more research conducted on purging disorder before it is added so definitively to an eating disorder diagnostic scheme, but I would have liked to see them discuss that issue in order to clarify the point.
In the other DSM-V models we have discussed on PBB (mood and anxiety disorders, personality disorders, PTSD, autism spectrum disorders), the proposed changes have been fairly radical in nature. The eating disorders proposal, on the other hand, is fairly conservative. Walsh and Sysko (2009) did an admirable job of proposing a system that would reduce reliance upon the EDNOS diagnosis and cluster similar behaviors with one another. That being said, do you see any strengths and/or weaknesses that went unaddressed in this discussion? Do you have a suggestion for an alternative model? Do you think changes to the system are even necessary in the first place? We look forward to hearing your thoughts.
************
If you would like to learn more about eating disorders and their treatment, we recommend the following items, all of which are available through our online store of scientifically-based psychological resources:
- Cognitive Behavior Therapy and Eating Disorders
by Christopher Fairburn
- Overcoming Binge Eating
by Christopher Fairburn
- If Your Adolescent Has an Eating Disorder: An Essential Resource for Parents
by Timothy Walsh
- Treatment Manual for Anorexia Nervosa: A Family-Based Approach
by James Lock, Daniel le Grange, Stewart Agras, and Christopher Dare
- Eating with Your Anorexic: How My Child Recovered Through Family-Based Treatment and Yours Can Too
by Laura Collins
- Dialectical Behavior Therapy for Binge Eating and Bulimia
by Debra Safer, Christy Telch, and Eunice Chen
- Eating Disorders
by Pam Keel
Mike Anestis is a doctoral candidate in the clinical psychology department at Florida State University




















Recent Comments