CHICAGO — Treatment outcomes for obese patients with binge-eating disorder differ by disease severity and negative affect, data from a large study of patients with this disorder show.
“We are trying to identify a particular subset of the population [that responds to a particular treatment],” Denise E. Wilfley, Ph.D., director of the Weight Management and Eating Disorders Program at Washington University in St. Louis, reported at the annual meeting of the Association for Behavioral and Cognitive Therapies.
The study evaluated three treatments for binge-eating disorder (BED): interpersonal therapy (IPT), behavioral weight loss (BWL), and guided self-help (GSH). “This is the first study to compare three different treatments for binge-eating disorder,” said Dr. Wilfley. Participants were also stratified by high versus low negative affect and by severity of bingeing.
According to the DSM-IV, people with BED eat a large amount of food with loss of control on at least 2 days a week for at least 6 months; they do not regularly engage in compensatory behaviors.
Dr. Wilfley said that people with this disorder tend to have low self-esteem and very high rates of health care use, traits similar to people with anorexia and bulimia nervosa. But unlike people with those conditions, people who have BED are more likely to be male and less likely to be white.
Given the large amount of food they consume, people with BED are more likley to be overweight or obese. “They're not just obese individuals,” said Dr. Wilfley, also professor of psychiatry at the university. “They are obese individuals with an eating disorder.”
The trial involved 205 participants and was conducted at three sites: Stanford (Calif.) University (data coordinating center), Washington University (clinical site), and Rutgers University (clinical site) in Piscataway, N.J. Participants were at least 18 years old, met the DSM-IV criteria for BED, and had a body mass index (BMI) between 27 and 45 kg/m
Patients who had a psychiatric or physical impairment that would preclude full participation, such as active suicidality, were excluded. Of the participants, 85% were female, and the average age was 49 years.
In terms of race, 82% were white; 13% were black, 4% were Hispanic, and 1% was Native American. Slightly more than half of the participants were college educated, and the average BMI among the participants was 36.
The participants were randomized to one of the three treatments. Participants in both the interpersonal therapy and the behavioral weight loss groups had 20 60-minute therapy sessions over a 24-week period.
The participants who were in the guided self-help group used bibliotherapy. They were asked to read “Overcoming Binge Eating,” by Dr. Christopher G. Fairburn (New York: the Guilford Press, 1995), a book that is aimed at teaching behavior change. This group also had one 55-minute and nine 25-minute therapy sessions over 24 weeks. The IPT group included 75 patients, the BWL group had 64 patients, and the GSH group had 66 patients.
There were no significant differences in patient characteristics among the three groups.
The researchers used the Beck Depression Inventory to stratify the participants according to high negative affect (HNA) and low negative affect (LNA).
Although they were apt to stay with interpersonal therapy, patients with HNA were significantly more likely to drop out of the behavioral weight loss treatment group than those with LNA. Those with LNA were much more likely to drop out of guided self-help.
Overall, treatment retention rates were significantly better among those treated with interpersonal therapy (93%) than with behavioral weight loss (72%) and guided self-help (70%).
The patients who were in the BWL group had a significantly better short-term weight loss than those in the other two groups, but this advantage disappeared by the 1-year follow-up.
The primary outcome measures in the trial were binge frequency and remission rates, defined as no binge eating in 28 days. The results showed that all three treatments had similar outcomes in treating binge eating disorder, associated eating disorders, and general psychopathology after 24 weeks.
The researchers followed the patients for 24 months and have analyzed the results for the first 12 months. The posttreatment data showed that interpersonal therapy was superior to the two other treatment options in those patients with severe binge eating.
In addition, HNA participants were more likely to do poorly on binge eating outcomes when the behavioral weight loss approach was used, compared with the IPT or guided self-help approach, over the course of the 1-year follow-up period.
When data for the 24-month follow-up period become available, clinicians treating BED may have even more valuable insights into the treatment of this disorder, the researchers said.