A total of 154 eligible patients were recruited and underwent randomized assignment between March 2002 and July 2005 (). Ninety-three (60.4%) were from Oxford, and 61 (39.6%) from Leicester. Five did not attend their initial assessment, all of whom had been assigned to the waiting list condition. Among the remainder (N=149), 57 (38.3%) had a diagnosis of bulimia nervosa and 92 (61.7%) a diagnosis of eating disorder not otherwise specified. Seven patients (4.7% of the full sample) fulfilled the DSM-IV research criteria for binge eating disorder. The characteristics of the sample are summarized in .
Baseline Characteristics of Patients With Eating Disorders Assigned to Waiting List Control Condition, Immediate CBT-Ef, Immediate CBT-Eba
Of the 154 patients, 53 were assigned to immediate CBT-Ef, 50 to immediate CBT-Eb, and 51 to the waiting list control condition, after which they received either CBT-Ef (N=25) or CBT-Eb (N=26). The study groups were balanced on all baseline factors except that patients assigned to immediate CBT-Eb were less likely to have a current major depressive episode or a history of anorexia nervosa (). Adjusting for these two factors in the analyses made no difference to the findings.
Suitability, Expectancy, and Attrition
The ratings of suitability and expectancy were high and did not differ between the two forms of CBT-E. Of the 149 patients who started treatment, 33 (22.1%) did not complete treatment or were withdrawn because of lack of response. The noncompletion figures were 14.0% (8/57) for the patients with bulimia nervosa and 27.2% (25/92) for those with eating disorder not otherwise specified (chi-square p=0.09).
Effects of Immediate Treatment Versus Delayed Treatment
There was little change in patients in the waiting list control condition, whereas there was substantial change in those in the two CBT-E conditions and no significant differences between them (). There were no significant effects of site. The mean changes in global EDE-Q score were −0.09 (95% CI=−0.28 to 0.10), −0.94 (95% CI=−1.28 to −0.61) and −1.17 (95% CI=−1.45 to −0.90) in the waiting list, CBT-Ef, and CBT-Eb conditions, respectively.
Clinical Measures at Baseline and 8 Weeks and Change Over 8 weeks in Patients Assigned to the Waiting List Control Condition (N=51), Immediate CBT-Ef (N=53), and Immediate CBT-Eb (N=50)a
Effects of CBT-Ef and CBT-Eb at End of Treatment and at 60-Week Follow-Up
There was a substantial response to treatment across all measures () and no significant differences between the two treatments; indeed, the mean absolute and change scores were almost identical for the two treatments (e.g., global EDE change: −1.51 [SD=1.35] versus −1.53 [SD=1.28] for CBT-Ef and CBT-Eb, respectively). By the end of treatment, half the overall sample (N=79; 51.3%) had global EDE scores below 1.74. There were no significant effects of site. The changes were greater in the patients who completed treatment; for example, at the end of treatment two-thirds (N=77/116, 66.4%) had a global EDE score below 1.74, and there was no difference between the two treatments (66.1% of the CBT-Ef group versus 66.7% of the CBT-Eb group).
Clinical Measures Over the Course of 20-Week Treatment and 60-Week Follow-Up in Patients With Eating Disorders Receiving CBT-Ef (N=77) or CBT-Eb (N=72)a
Compliance with follow-up was high, with 95.1% (331/348) of the assessments successfully completed. Of the 116 patients who entered follow-up, eight had additional treatment and nine had one to five brief “booster” sessions. The changes were well maintained across the follow-up period. At 60-week follow-up, 50.0% of the overall sample (N=77) had a global EDE score below 1.74. The mean changes in global EDE in the CBT-Ef and CBT-Eb groups were similar at 1.36 (SD=1.42) and 1.33 (SD=1.30), respectively.
Eating Disorder Diagnosis as a Moderator of Treatment Response
The patients with bulimia nervosa and eating disorder not otherwise specified entered the study with very similar psychopathology, as described in a separate report (5
). This similarity was also present at 8 weeks (data not shown), and on repeated-measures analysis of variance there was no significant main effect of diagnosis at this point. There were also no significant differences between the two diagnostic groups at end of treatment and at 60-week follow-up. At the end of treatment, 52.7% (30/57) of the patients with bulimia nervosa and 53.3% (49/92) of those with eating disorder not otherwise specified had a global EDE score below 1.74, and at 60-week follow-up these figures were 61.4% (35/57) and 45.7% (42/92), respectively.
Additional Psychopathology and the Relative Effects of CBT-Ef and CBT-Eb
In this exploratory analysis, the clinicians’ ratings of their patients’ mood intolerance, clinical perfectionism, low self-esteem, and interpersonal difficulties were used to identify patients with marked additional psychopathology of the type that CBT-Eb was designed to target. Outcomes for these patients were compared with those of the remainder in relation to the form of CBT-E received. A notable pattern of findings emerged. This was clearest when at least two of the domains had been rated as moderate or major clinical problems. This applied to 54 patients (54/138, 39.1%). This subgroup with “complex” additional psychopathology responded less well in general than the “less complex” subgroup; their mean global EDE score at 60-week follow-up, adjusted for baseline, was 2.09 (95% CI=1.74–2.44), compared with 1.77 in the less complex subgroup (95% CI=1.49–2.05; overall adjusted p value on repeated-measures analysis of covariance, p=0.041), and 48% (95% CI=35–61) had a global EDE score below 1.74, compared with 60% (95% CI=49–70) of the less complex subgroup.
Within the complex subgroup of patients, those who received CBT-Eb had consistently lower adjusted global EDE scores than those who received CBT-Ef (), and they were more likely to have scores below 1.74 (see ; e.g., at 60-week follow-up 60% [95% CI=40–79] versus 40% [95% CI=22–58]). The reverse pattern of findings was consistently present among the less complex patients, with CBT-Ef proving superior to CBT-Eb (see and ).
Global Eating Disorder Examination Scores of Patients With Complex and Less Complex Psychopathology Receiving CBT-Ef or CBT-Eb Over the 60-Week Follow-Up Period, Adjusted for Baseline Scorea
Relative Effects of the Two Forms of CBT-E in Patients With Complex and Less Complex Additional Psychopathologya