In the United States, poor adherence accounts for up to 70% of all medication-related hospital admissions, resulting in $100 billion in healthcare costs annually Adherence rates have been reported as low as 0% in pediatric patients. Reasons for non-adherence are multifactorial. The most important determinants of non-adherence are consistently documented as complexity and duration of treatment regimens, as well as forgetfulness. Thus, children undergoing difficult hematopoietic stem cell transplants (HSCT) that require medication indefinitely are at high risk for medication non-adherence.

Only 4 published studies exist regarding adherence in pediatric HSCT. None address adherence to immunosuppressant medication, nor are they RCTs. Second, the complexity of most interventions for adherence is counter to the geographic, resource, and time constraints families of chronically ill children face. Adherence interventions based on conventional behavior theory have been cumbersome for families already stressed due to chronic illness. BE design is a significant paradigm shift to a simpler, less onerous approach that can engage those patients and families that would otherwise forego complicated adherence interventions. Although mHealth adherence apps are a widely available, simple, and innovative approach to addressing these problems, a third gap relates to poor usability. For example, a recent review of pediatric adherence apps found that none identified individual barriers to adherence, and nearly all were designed for adults. Thus, there is an urgent need to develop and evaluate innovative, accessible, and evidence-based approached to adherence among children receiving HSCT to prevent morbidity and mortality from GVHD.

The impact of non-adherence on clinical outcomes is largely unknown in pediatric HSCT. poor adherence is generally associated with adverse outcomes, including complications, hospital admissions, and even death. The societal burden of cancer care and HSCT is substantial and likely to increase based on the growing number of transplants each year. Clinicians and researchers have focused on GVHD prevention to minimize unnecessary treatment-related deaths. Acute GVHD develops in the first 100 days post-transplant. Children that develop acute GVHD have a 30% to 50% chance of survival. Morbidity and mortality due to GVHD can be decreased through prophylactic use of immunosuppressants. Although these medications are costly and produce unpleasant side effects, adherence is critical to decrease complications, reduce readmissions, and ultimately increase quality of life and survival.

Adherence is complex, but ultimately, the final common pathway to adherence is human behavior. In pediatrics, adherence is largely dependent on parents. As the primary caregivers, they are responsible for ensuring children receive the prescribed therapy correctly. In a high-risk HSCT population, caregivers are isolated with their child due to infection risk and must manage challenging treatment regimens at home, often with limited time and support. Complex behavioral interventions, typically employed to address adherence, are difficult to deliver and manage in the context of these daily tasks. Alternatively, behavioral economics (BE) theory suggests that small "nudges" can produce and sustain behavior change. A BE approach is a significant paradigm shift and assumes decision-making can be influenced through low-intensity interventions to lead patients to optimal choices. Improved adherence to medication and exercise programs using BE designed interventions in adults have been positive. Within pediatrics, BE has been successful in reducing childhood obesity, increasing vaccination rates, and improving adherence rates to infant HIV medications.