Predicting meaningful outcomes to medication and self-help treatments for binge-eating disorder in primary care: The significance of early rapid response.

Binge-eating disorder (BED), a formal eating-disorder diagnosis in DSM-5 (APA, 2013), is defined by recurrent binge eating, marked distress about binge eating, and the absence of extreme weight compensatory behaviors. BED is prevalent and is associated strongly with obesity and biopsychosicial problems (APA, 2013). Although some psychological and medication treatments have varying levels of effectiveness for BED, many patients fail to achieve remission from binge-eating and most fail to achieve significant weight loss (Reas & Grilo, 2014). Finding reliable predictors of treatment response could inform treatment prescriptions but this has been challenging (Grilo, Masheb, & Crosby, 2012). Rapid response (i.e., substantial improvements in symptoms during the early weeks of treatment) has been found to significantly predict treatment outcomes across diverse psychiatric problems, including medication and CBT treatments for depression (Taylor, Freemantle, Geddes, & Bhagwagar, 2006; Hardy et al., 2005) and bulimia nervosa (Sysko et al., 2010; Wilson et al., 2002). In a series of four studies, Grilo et al. (Grilo, Masheb, & Wilson, 2006; Grilo & Masheb, 2007; Grilo, White, Wilson, Gueorguieva, & Masheb, 2012; Masheb & Grilo, 2007) extended the rapid response findings to BED in several ways. First, the definition of rapid response was informed empirically using receiver operating characteristic (ROC) curves. These methods yielded “reliable” findings across studies that 65%–70% reductions in binge-eating by the fourth treatment week optimally predicted remission. Second, rapid response predicted significantly greater reductions in eating-disorder pathology in all four studies and greater weight loss in three studies (Grilo et al., 2006; Grilo & Masheb, 2007; Grilo et al., 2012). Third, rapid response was unrelated to nearly all baseline characteristics in the four studies suggesting rapid responders are not just “easy” patients nor do they show individual differences in demographic or clinical severity. Fourth, rapid response had varied prognostic significance across different treatments for BED (Grilo et al., 2006; 2012). Finally, the longer-term prognostic significance of rapid response to treatment for BED was established in the one study with follow-up (Grilo et al., 2012). Further research on rapid response is needed to establish longer-term significance and to extend findings to additional interventions (e.g., scalable treatments such as “self-help” CBT (shCBT) (Wilson & Zandberg, 2012)) and to broader health care settings with more diverse patient groups. One study with depression found that “sudden gains” with CBT had less predictive significance in routine clinical settings than in specialist settings (Hardy et al., 2005). Members of minority groups with BED receive most of their health care from primary care (Marques et al., 2011) and it is uncertain whether “effective” treatments delivered by specialists are as effective when delivered by generalists. The present study examined rapid response among patients with BED participating in a treatment study in primary care settings (serving racially and ethnically diverse persons) testing anti-obesity medication (sibutramine (Wilfley et al., 2008)) and shCBT, alone and in combination. We examine whether rapid response was related to patient characteristics and to outcomes through 12-months of follow-up after completing treatments.