Mediators of 12-Month Outcomes of Two Internet Interventions for Youth With Type 1 Diabetes

Type 1 diabetes is one of the most common and challenging chronic illnesses affecting youth in the United States, with projected estimates of the incidence increasing by 23%, from 166,018 in 2010 to 203,385 in 2050 (Imperatore et al., 2012). In adolescence, youth with type 1 diabetes face considerable challenges during this period of physiological, psychosocial, and cognitive development. Adolescents assume greater responsibility for their diabetes self-management, but carrying out a complex and demanding treatment regimen is difficult during a developmental phase when peer acceptance is a priority (Delamater, 2009). Adolescents with type 1 diabetes often exhibit poorer metabolic control and self-management along with increased psychosocial stress, distress, and lower quality of life (QOL) compared with younger children and adults with type 1 diabetes (Insabella, Grey, Knafl, & Tambolane, 2007). Given the challenges faced by adolescents with type 1 diabetes, interventions are needed to improve self-management and protect them against deterioration of metabolic control and poor psychosocial outcomes. Standards of care for youth with type 1 diabetes identify the importance of self-management education (American Diabetes Association, 2013; Silverstein et al., 2005), and evidence supports that psychosocial interventions focused on self-management have the potential to improve metabolic control of type 1 diabetes as well as QOL in youth (Anderson, Brackett, Ho, & Laffel, 1999; Grey, Boland, Davidson, Li, & Tamborlane, 2000; Laffel et al., 2003; Nansel, Iannotti, & Liu, 2012; Wysocki et al., 2007). A recent pilot study of an Internet-based psychosocial intervention also had promising results on self-management and problem solving (Mulvaney, Rothman, Wallston, Lybarger, & Dietrich, 2010). Even in successful interventions, however, the mechanism of change is not always clear, nor which components of the intervention were effective. While evaluating the main effects of interventions is critical to improving health outcomes, it is equally important to examine moderators and mediators of randomized clinical trials—even those that are unsuccessful—to determine how and for whom interventions may work (Kraemer, Wilson, Fairburn, & Agras, 2002). Examining mediators provides evidence for the mechanisms of change, which offers direction for program implementation and future research (Kazdin, 2007). Investigating mediators of interventions also allows for testing the theoretical basis and the effect of interventions on separate outcomes (La Greca, Silverman, & Lochman, 2009). Although Internet-based interventions have been successful in improving outcomes in pediatric populations, most have not explicitly tested mediators and moderators of the effects. For example, a family cognitive behavioral therapy delivered over the Internet was successful in reducing pain intensity and improving function in youth with chronic pain (Palermo, Wilson, Peters, Lewandowski, & Somheghi, 2009), but the researchers did not test for moderators of the effects. Similarly, an Internet-based educational program for youth with asthma resulted in reduced asthma-related emergencies and a decrease in the daily use of rescue medication (Runge, Lecheler, Horn, Tews, & Schaefer, 2006). However, the authors did not report on increased asthma knowledge as a mediator of these effects. As Ritterband et al. (2009) note, “testing which mechanisms of change within the model are responsible for bringing about behavior change … is critical to Internet intervention research” (p. 23). In type 1 diabetes, it is important to test for both mediators and moderators of interventions on psychosocial outcomes, such as QOL, as well as clinical outcomes, such as metabolic control. Progress has been made in determining moderators of the effects of interventions for youth with type 1 diabetes, such as age (Graue, Wentzel-Larsen, Hanestad, & Sovik, 2005), gender (Whittemore et al., 2012), and family structure (Ellis et al., 2007), but few studies have examined mediators of intervention effects. In one of the only studies to do so, the authors found that the positive effects of multisystemic therapy on metabolic control were mediated by increased blood glucose testing (Ellis et al., 2007). Another study found that improvements in parent–child communication and problem solving mediated the effects of behavioral family systems therapy on metabolic control, adherence, and family conflict (Wysocki et al., 2008). To our knowledge, no other research on mediators of intervention effects in youth with type 1 diabetes has been conducted.