STUDY SUMMARY: Both broad and focused CBT delivered results
Conducted at 2 eating disorder centers in the United Kingdom, this RCT included 154 patients, 18 to 65 years of age, who met DSM-IV criteria for either bulimia or eating disorder NOS. Exclusion criteria included prior treatment with CBT or other evidence-based treatment for the same eating disorder, and a BMI ≤17.5.
Most of the patients were female (95.5%) and white (90.3%), with a median age of 26 years and a median duration of eating disorder of 8.6 years. Sixty-two percent of the patients had a diagnosis of eating disorder NOS, and 38% were diagnosed with bulimia. Half of the patients had another current psychiatric diagnosis—a major depressive disorder, an anxiety disorder, or substance abuse.
The patients were randomized into 4 groups: Two received immediate treatment, and the other 2, referred to as waiting list controls, waited 8 weeks before beginning treatment. Treatment consisted of 1 of 2 forms of CBT-E, an enhanced form of CBT used to treat adult outpatients with eating disorders. Patients either received CBT-Ef, a focused form of CBT that exclusively targets eating disorder psychopathology, or CBT-Eb, a broader form of therapy that also addresses other problems that are common in patients with eating disorders, such as perfectionism and low self-esteem.
Both types of CBT-E featured a 90-minute preparatory session, 20 50-minute sessions, and 1 review session 20 weeks after completion of treatment. In the first 4 sessions, CBT-Ef and CBT-Eb were identical—addressing the eating disorder exclusively. CBT-Ef continued to focus on the eating disorder for the rest of the sessions, while subsequent CBT-Eb sessions also dealt with mood intolerance, interpersonal difficulties, and related issues. Five therapists—4 psychologists and 1 nurse-therapist—conducted the treatments.
Patients were weaned from ongoing psychiatric therapy during the study, but those who were on antidepressant therapy (n=76) were able to continue it. Patients were assessed before treatment, at the end of the waiting period for those in the control groups, after 8 weeks of treatment, at the end of treatment, and 20, 40, and 60 weeks after completion of treatment. (Twenty-two percent of the enrollees did not complete treatment.)
Primary outcomes were based on the Eating Disorder Examination (EDE), administered by assessors who were not involved in the treatment and were blinded to the patients’ group assignment. Change in severity of eating disorder features was measured by the global EDE score (0-6) and attaining a global EDE score <1.74 (<1 standard deviation above the community mean).
No treatment vs CBT. The waiting period left little doubt of the short-term efficacy of CBT: After 8 weeks, there was significant improvement in eating disorder behaviors and overall severity in both the CBT-Ef and CBT-Eb groups (EDE scores fell from 4.15 at baseline to 3.26 and from 4.04 to 2.89, respectively). In the same time period, scores for the waiting list control groups remained flat (from 4.08 at baseline to 3.99).
At the end of treatment and at the 60-week follow-up, patients in both forms of CBT-E showed significant improvement across all measures, with no significant difference between treatments. By the end of treatment, 66.4% of those who completed all of the CBT sessions had global EDE scores <1.74 (considered clinically significant).
Subgroup analysis offers opportunity for fine-tuning
When analyzed separately, the patients with bulimia and those with eating disorder NOS did equally well at the end of treatment: 52.7% of those with bulimia and 53.3% of those with eating disorder NOS had global EDE scores <1.74. At the 60-week follow-up, the patients with bulimia maintained their improvement slightly more: 61.4% had global EDE scores <1.74, compared with 45.7% of the patients with eating disorder NOS.
The researchers also compared the outcomes of patients with the most complex additional psychopathology with those of patients with less complex problems. Greater complexity was defined as moderate ratings in at least 2 of the following domains: mood intolerance, clinical perfectionism, low self-esteem, and interpersonal difficulties.
Broad focus more effective for high complexity. Overall, those in the more complex subgroup did not respond as well; 48% had global EDE scores <1.74, vs 60% of those in the less complex group. However, those in the more complex subgroup did better with the broad form of CBT (at 60-week follow up, 60% had scores <1.74 with CBT-Eb, compared with 40% in the CBT-Ef treatment arm), while the less complex subgroup did better with the more tightly focused CBT-Ef. 2
WHAT’S NEW: Evidence supports CBT for NOS diagnosis
The most recent (2004) Cochrane review of “psychotherapy for bulimia nervosa and binging” included 40 RCTs of patients with bulimia, binge-eating disorder, and eating disorder NOS with recurrent binge-eating episodes (included in 7 studies). While the review confirmed that CBT is effective for bulimia and “similar syndromes,” it identified a need for larger and higher quality trials of CBT, particularly in patients with eating disorder NOS.1 The study reviewed in this PURL—the first large, high-quality trial to include a number of patients with eating disorder NOS—provides strong evidence that CBT is effective for this group of patients.2
