Predictors of child weight loss and maintenance among family-based treatment completers.

Overweight and obesity affect 32% of children in the United States (Ogden, Carroll, Kit, & Flegal, 2012) and are associated with negative physical and psychosocial health sequelae (Puhl & Latner, 2007; Reilly et al., 2003). Family-based behavioral weight loss treatment (FBT), which targets both child and parent weight-related behaviors, is the current treatment of choice for pediatric obesity (United States Preventive Services Task Force, 2010; Wilfley, Tibbs, et al., 2007), and maintenance treatments (MTs) can extend its effects for up to two years (Wilfley, Stein, et al., 2007; Wilfley et al., 2010). Although children generally maintain relative weight changes achieved at 2-year follow-up over longer periods (Epstein, Valoski, Wing, & McCurley, 1994), initial non-response and relapse are challenges for many children (Wilfley, Tibbs, et al., 2007). In our current healthcare environment, it is essential to identify children who are most likely to benefit from interventions so as to inform the allocation of limited treatment resources. Gaining a better understanding of predictors of outcome can assist in this way, including targeting children who would most benefit from existing treatments, and modifying future interventions to help maximize effectiveness. Examining general predictors can help identify patients who will respond more or less favorably to treatment, regardless of the type of treatment provided. Moderators are treatment-specific predictors of outcome that can help identify patients who may respond more favorably to one type of treatment than another (Kraemer, Wilson, Fairburn, & Agras, 2002). Although general predictors can assist with patient selection, treatment-specific moderators may have more clinical utility, such as when wanting to match patients to treatment. To date, few studies have investigated predictors of FBT outcome. Some (Reinehr, Kleber, Lass, & Toschke, 2010; Sabin et al., 2007), but not all (Moens, Braet, & Van Winckel, 2010), studies have demonstrated that younger children are more likely to succeed than older children in weight control programs, perhaps because their weight-related habits are less ingrained and more amenable to change. Higher initial body weight also predicts better outcome (Braet, 2006; Goossens, Braet, Van Vlierberghe, & Mels, 2009; Moens et al., 2010), and some studies suggest that females have improved treatment response (Epstein, Koeske, Wing, & Valoski, 1986), although findings are mixed (Epstein, Valoski, et al., 1994). Potentially modifiable factors associated with better short- and long-term outcome across treatments include early treatment response (Goldschmidt et al., 2011; Jelalian et al., 2008), which may be a proxy for initial motivation or stronger engagement in treatment; better overall psychosocial functioning, including greater social support (Braet, 2006; Epstein, Valoski, et al., 1994; Moens et al., 2010) and lower impulsivity and food reinforcement (Best et al., 2012), all of which may facilitate adherence to treatment recommendations; and familial factors such as greater parent weight loss (Wrotniak, Epstein, Paluch, & Roemmich, 2004) and lower parental psychopathology (Epstein, Wisniewski, & Weng, 1994; Frohlich, Pott, Albayrak, Hebebrand, & Pauli-Pott, 2011; Moens et al., 2010), which could operate through parents' abilities to provide healthy modeling and support for behavior change. To date, there have been no studies examining predictors of outcome following MT. Moreover, there is an incomplete understanding of patient moderating variables predicting response among different approaches with demonstrated average efficacy across children (Epstein et al., 2012; Yildirim et al., 2011). Our group previously tested two MT approaches designed to assist youth in maintaining their weight loss following standard FBT (Wilfley, Stein, et al., 2007). Behavioral skills maintenance (BSM) focused on helping families develop behavioral weight maintenance skills, including self-regulatory and relapse prevention strategies (e.g., enhancing efficacy to cope with situations presenting a high risk for behavioral lapses), whereas social facilitation maintenance (SFM) was designed to help families modify their social environment to support weight maintenance, emphasizing peer-related (e.g., lack of social support for healthy behaviors) and social self-perceptual (e.g., body image) barriers to long-term weight maintenance. Both MTs led to improved weight outcomes over two years when compared to a control condition that received no MT, and children with lower initial levels of social problems were found to particularly benefit from SFM, perhaps because they could more readily implement the basic SFM skills (Wilfley, Stein, et al., 2007). However, other predictors that could theoretically promote or inhibit weight change both throughout the duration of treatment, and within the specific MT conditions, were not examined in the context of our original trial, thus limiting the data's clinical applicability. Investigating a wider range of putative general and treatment-specific predictors could assist with treatment matching, as well as with designing or enhancing treatments to optimally facilitate weight change across the spectrum of overweight youth and their families. The purpose of the current research was to expand upon the results of our randomized controlled trial (which reported on the outcome of MT interventions following standard FBT(Wilfley, Stein, et al., 2007) by identifying general predictors and treatment-specific moderators of outcome among FBT completers beyond the initially identified social problems effect. Based on the previous literature (Braet, 2006; Epstein et al., 1986; Epstein, Valoski, et al., 1994; Epstein, Wisniewski, et al., 1994; Frohlich et al., 2011; Goossens et al., 2009; Jelalian et al., 2008; Moens et al., 2010; Reinehr et al., 2010; Sabin et al., 2007; Wrotniak et al., 2004), we hypothesized that the following factors would be associated with improved child weight outcomes in both the short- and long-term, across MT treatments: being female; younger age, and higher z-BMI at initiation of FBT; greater parent weight change during FBT; and better child and parent psychosocial functioning, including general- and eating-related psychopathology, self-efficacy, and family support. We further expected that BSM would particularly benefit youth with lower initial self-efficacy as compared to SFM and control, since BSM specifically aimed to enhance self-efficacy in changing weight-related behaviors. Correspondingly, we expected SFM to particularly benefit those with poorer initial peer support and higher initial eating-related psychopathology (including shape and weight concerns) as compared to BSM and control, since SFM specifically sought to improve functioning in these domains.