This study examined the acceptability and efficacy of a brief guided self-help program, based on cognitive-behavioral principles, for the treatment of recurrent binge eating relative to treatment as usual. Our study employed a randomized clinical trial design yet involved features more commonly found in effectiveness studies, including delivering the treatment in a primary care context and by staff with less education than is typical in efficacy studies, and adopting a broader definition of eating disorders (i.e., allowing for greater variability in diagnoses and thereby more closely capturing eating disorder cases that might present in routine clinical practice). As summarized in , 48% of the sample was diagnosed with BED, 10.6% met criteria for BN, and 41.6% of the sample met our criteria for recurrent binge eating. Exploratory moderator analyses failed to show differential treatment effects across eating disorder diagnoses, yet we caution that the percentage of individuals with BN was too small to detect differences. Previous research has shown CBT-GSH to be effective both with BED (Wilson et al., in press
) and with BN (Mitchell et al., 2006), yet the latter study awaits replication. Hence, until further studies are conducted where power is adequate to test efficacy of CBT-GSH for the treatment of BN, we conservatively conclude that CBT-GSH is a viable treatment for recurrent binge eating in individuals who do not meet criteria for BN or anorexia nervosa.
Although the particular outreach approach to health plan members proved highly challenging, requiring large scale mailings (Debar et al., 2009
), once participants agreed to enter the trial, acceptability of the CBT-GSH program as reflected in attendance rates was high. Dropout was low and consistent with completion rates reported in other trials providing guided self-help for the treatment of binge eating disorder which found dropout rates of 10% (Carter & Fairburn, 1998
) or 13% (Grilo & Masheb, 2005
), respectively. Moreover, participants appeared to agree with the rationale for CBT-GSH which was presented during the first session: the mean expectancy rating for the suitability of this treatment for their eating problem (obtained at session 2) was 4.16 on a scale where 5 was the maximum score. Of note, suitability ratings were not predictive of treatment outcome. Our design does not permit testing the hypothesis that suitability ratings would be predictive of relatively greater adherence to CBT-GSH versus another treatment because our comparison condition, TAU, did not require patients to follow a specific regimen.
Treatment in this study was delivered by Master’s level therapists with experience in using CBT for depression. A majority of patients in our study exhibited comorbid psychopathology (see ). Roughly 60% had a comorbid axis I diagnosis; 15% of the CBT-GSH group were diagnosed with major depression. Rates of comorbid Borderline Personality Disorder were low. The level of therapist training and skill necessary for effective administration of CBT-GSH remains undetermined (Sysko & Walsh, 2008
). Inexperienced and unsupervised health care providers with minimal training in CBT-GSH appear ineffective (Walsh, Fairburn, Mickley, Sysko, & Parides, 2004
). Even if successful CBT-GSH requires specific therapist selection, training, and supervision, it would still provide a briefer, less costly, and more readily disseminable intervention to a wider range of health care providers than specialty psychotherapy (Wilson et al., in press
The primary aim of our study was to evaluate CBT-GSH against TAU. All participants were informed about the HMO’s options for treating binge eating. Our data show that most participants in both conditions utilized health services during the 12 weeks following randomization and thus had opportunity to request specific services for their eating problem. The large number of participants receiving psychotropic medications (typically antidepressants and, to a lesser degree anxiolitics) speaks to the considerable level of distress or comorbid psychopathology in this sample. Yet, as shown in , only few participants were treated specifically for an eating disorder outside the context of the CBT-GSH treatment condition. Similar to services offered in most health care settings, treatment for eating disorders within the health plan largely consisted of nonspecific case management rather than the provision of evidence based CBT treatment for eating disorders. Indeed, several previous studies have documented the infrequent use of care targeted specifically to treating the eating disorder (Striegel-Moore et al., 2008
; Striegel-Moore et al., 2000
The post-treatment and one year follow-up abstinence rates from binge eating (our primary outcome variable) for CBT-GSH of 63% and 64% respectively are consistent with findings from recent research on the efficacy of CBT-GSH for the treatment of BED. For example, Wilson et al. (in press)
obtained rates of 58% and 60% at post-treatment and one year follow-up. Moreover, favorable results were also observed for several of the secondary outcomes, including improvements on measures of eating related psychopathology (specifically, eating-, weight- and shape concerns, and restraint), as well as on measures of depression and functional impairment.
The effect size estimates for abstinence from binge eating further underscore the clinical significance of our results. For every three patients (at 6 months) or 5 patients (at 12 months) treated with CBT-GSH, one more failure (i.e., a patient who did not achieve abstinence) was observed in TAU. Even though CBT-GSH lost some of its superiority over TAU over time (NNT decreased from 3 at post-treatment and 6-month follow-up to 5 at 12-months), this relative decline in superiority is modest. Moreover, we note that the relative decline in superiority appeared to occur because of improvements in the TAU group rather than because of a loss of earlier gains in the CBT-GSH group. The cost effectiveness of CBT-GSH relative to TAU is the subject of a separate report (Lynch et al., 2009
). The results also compare favorably with outcomes for BED of specialty psychological therapies such as manual-based CBT and IPT (Wilson et al., 2007
). As such, they add to the accumulating evidence that recurrent binge eating can be effectively treated with a brief and easily disseminable treatment.
Similar to studies of CBT or CBT-GSH for the treatment of BED (Grilo & Masheb, 2005
; Wilson et al., in press
), a population where overweight or obesity is common and weight loss therefore a desirable treatment outcome (Wilfley, Bishop, Wilson, & Agras, 2007
), our study found that CBT-GSH had no significant effect on weight. In part this may reflect the fact that the intervention does not target weight loss (although we point out that participants in the Grilo and Masheb (2005
) study also did not lose significant amounts of weight in the BWL condition). An unplanned post-hoc analysis found a small effect for BMI when comparing participants who had achieved abstinence from binge eating versus those who had not. Of note, the latter group experienced a slight weight gain over the course of the study. This finding is consistent with data from a longitudinal study of women with bulimia nervosa or binge eating who were found to gain weight at an accelerated rate compared to healthy women (Fairburn et al., 2003
Several limitations need to be considered. These include the insufficient power for testing predictors or moderators of treatment outcome. Surprisingly, we did not find a significant predictor effect of negative affect (defined by BDI scores) given previous studies in which high negative affect predicted a poorer treatment response (Masheb & Grilo, 2008
; Stice, Bohon, Marti, & Fischer, 2008
). Another limitation was the demographic homogeneity of our sample. Men or individuals representing ethnic minority populations have been shown to suffer from binge eating disorders (Alegria, et al., 2007
; Cachelin & Striegel-Moore, 2006
; Hudson, Hiripi, Pope, & Kessler, 2007
; Taylor, Caldwell, Baser, Faison, & Jackson, 2007
), yet few men or Hispanic individuals were included in our sample despite outreach efforts and the availability of assessment and intervention materials in Spanish language for Hispanic health plan members (the largest ethnic minority group in the HMO’s geographic area).
The strengths of the study include the health maintenance organization setting, the use of the EDE, good retention of patients in the sample through follow-up, and a broader sample of patients (including many with EDNOS) than more narrowly defined BED or BN samples from previous studies of CBT-GSH. As such, we have provided novel findings for the disseminability of evidence based CBT-GSH.