a1 Harris Center, Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
a2 National Institute of Mental Health, Section on Developmental Genetic Epidemiology, Bethesda, MD, USA
a3 Neuropsychiatric Research Institute, Fargo, ND, USA
a4 Department of Clinical Neuroscience, University of North Dakota School of Medicine and Health Sciences, Fargo, ND, USA
a5 Department of Counseling and Applied Educational Psychology, Northwestern University, Boston, MA, USA
Objective Anorexia nervosa (AN) and bulimia nervosa (BN) are marked by longitudinal symptom fluctuations. DSM-IV-TR does not address how to classify eating disorder (ED) presentations in individuals who no longer meet full criteria for these disorders. To consider this issue, we examined subthreshold presentations in women with initial diagnoses of AN and BN.
Method A total of 246 women with AN or BN were followed for a median of 9 years; weekly symptom data were collected at frequent intervals using the Longitudinal Interval Follow-up Evaluation of Eating Disorders (LIFE-EAT-II). Outcomes were ED presentations that were subthreshold for ≥3 months, including those narrowly missing full criteria for AN or BN, along with binge eating disorder (BED) and purging disorder.
Results During follow-up, most women (77.6%) experienced a subthreshold presentation. Subthreshold presentation was related to intake diagnosis (Wald χ2=8.065, df=2, p=0.018). Individuals with AN most often developed subthreshold presentations resembling AN; those with BN were more likely to develop subthreshold BN. Purging disorder was experienced by half of those with BN and one-quarter of those with AN binge/purge type (ANBP); BED occurred in 20% with BN. Transition from AN or BN to most subthreshold types was associated with improved psychosocial functioning (p<0.001).
Conclusions Subthreshold presentations in women with lifetime AN and BN were common, resembled the initial diagnosis, and were associated with modest improvements in psychosocial functioning. For most with lifetime AN and BN, subthreshold presentations seem to represent part of the course of illness and to fit within the original AN or BN diagnosis.
(Received August 17 2009)
(Revised November 13 2009)
(Accepted November 13 2009)
(Online publication January 05 2010)
Some of the data in this paper were presented at the Eating Disorders Research Society Meeting in Montreal, Canada, September 2008.