The BCD-ED system appears to have a number of advantages, most notably reducing the number of individuals who would receive an EDNOS diagnosis, while preserving a three-category system resembling that of DSM-IV. This scheme also offers an advantage for diagnosing individuals with eating disorders outside of specialist settings, where a comprehensive psychiatric assessment may not be feasible (e.g., primary care). Individuals can be grouped into a broad category (e.g., AN-BSD) using relatively limited information, including body mass index, clinically significant distress or functional impairment, and ruling out other Axis I and general medical conditions. The BCD-ED scheme also offers more specific diagnostic information by including sub-groups within the broad categories, which could be used to inform clinical care.
However, there are also a number of concerns about adopting this system. Individuals classified in one of the broad categories of the BCD-ED scheme (e.g., AN-BSD) may exhibit a different symptom constellation than prototypic individuals with DSM-IV defined eating disorders (e.g., AN), and may not share all of the characteristics of these individuals, including the course and outcome of their eating disorder. Thus, since the existing literature base on DSM-IV AN will likely not apply to all individuals who are included in the AN-BSD category, clinicians may be misguided in their recommendations regarding treatment. Further, as data on the clinical characteristics of EDNOS are limited, the designation of several of the proposed sub-groups in the BCD-ED scheme is based more on clinical anecdote than on an established literature. The possibility of overdiagnosis, as noted above, is another concern with the BCD-ED scheme, but might be satisfactorily addressed through the use of a robust measure of clinically significant distress and impairment.
In addition, other options exist for the organization of the diagnostic criteria proposed in Appendix II
. For example, the subgroup AN-BSD with significant weight loss but remaining at or above minimally acceptable body weight (nnn.13) might be incorporated into Typical Anorexia Nervosa (nnn.11) with a ‘novel’ definition of minimally acceptable weight, or into AN-BSD-NOS (nnn.14). The proposed Typical Bulimia Nervosa (nnn.21) and Bulimia Nervosa, low frequency (nnn.22) subgroups could be combined into a broader Bulimia Nervosa subgroup. Similarly, Typical Binge Eating Disorder (nnn.31) and Binge Eating Disorder, low frequency (nnn.32) could be joined. The clinician could specify the frequency of binge or out of control eating episodes and of purging behavior, rather than assigning individuals with episodes occurring less than once per week to a different subgroup of BN-BSD.
For the purging disorder subgroup (nnn.23), it might not be appropriate to require loss of control eating as a diagnostic criterion, as some studies have not required the presence of such eating episodes (27
). Also, individuals with purging disorder have been grouped with individuals with AN in some empirical studies (45
), suggesting that this subgroup might be better located within AN-BSD rather than within BN-BSD as it is in the current proposal.
Other options could be considered for the nosological placement of subgroups within the BCD-ED scheme, including non-purging BN. In the current proposal, recurrent purging behavior is a required feature of the BN-BSD category, implying that non-purging BN is better grouped with BED than with BN; however, some data suggest non-purging BN to be intermediate in severity between BN and BED (21
). As with other decisions involved in the construction of BCD-ED, this is at least somewhat arbitrary due to limited research, and might be reconsidered on the basis of additional information.
The BCD-ED scheme provides a cross-sectional categorization of the eating disorders for clinical purposes, and does not address diagnostic crossover -- the migration of individuals between categories. In addition, this scheme does not address the definition of recovery from an eating disorder; therefore, like DSM-IV, it does not provide criteria for when an individual should no longer be categorized as having an eating disorder or moves from one category to another. Investigators may wish to develop more stringent and more explicit inclusion and exclusion criteria, such as those employed for the prototypical categories described in the three broad categories. Finally, the BCD-ED would be a major change in how eating disorders are categorized, and would be best implemented if similar changes were made throughout DSM-V. These concerns, and others noted above, must be weighed against potential gains before a decision is made to incorporate the BCD-ED scheme in DSM-V.