Nonadherence to immunosuppression is associated with an increased risk for organ rejection, allograft vasculopathy, and death (De Geest et al., 2014). Immunosuppression nonadherence has been found to be a factor in up to 90% of late acute rejection events that occur after the first year following transplant, and in 13% to 26% of deaths among heart transplant recipients in single-center research studies (De Geest et al., 2005). A prospective cohort study found that for individuals who were nonadherent after their first year following transplant, the risk of a negative clinical event was doubled (Dobbels et al., 2004). In addition to the significant clinical outcomes, nonadherence to the therapeutic regimen is also associated with increased healthcare costs (De Geest et al., 2005). Despite the importance of adherence to immunosuppression medications following heart transplantation for the prevention of graft rejection and preservation of graft function, medication nonadherence rates following heart transplantation in the literature range from 20% to as high as 37% (Leentje De Bleser et al., 2009; Dobbels et al., 2017).
Nonadherence may occur directly through the failure to recall the intention to take the medication as intended, or indirectly through illness representations that can be shaped by cognitive function. Time since transplant, perceptions related to the necessity of medications, and the perceived impact of transplantation on life are factors that have been associated with higher rates of nonadherence in some solid organ transplant recipient populations (De Geest et al., 2014; Massey et al., 2015). Pre-transplant medication nonadherence has been found to predict post-transplant nonadherence (De Geest et al., 2014). Heart transplant recipients are at unique risk for cerebral hypoxic injury both before transplantation as a result of pathophysiologic processes that can occur during heart failure and treatment with mechanical circulatory support devices (MCSD), and following transplant as a result of cardiopulmonary bypass, heart structural remodeling, and inflammatory processes (Acampa et al., 2016; Cho et al., 2017). These mechanisms and their impact on executive function and working memory potentially influence the ability to adhere after transplantation. Additionally, evaluation of these variables has become increasingly important to assess in the context of aging, with the majority of individuals undergoing transplantation in their 50s, and median survival extending past 11 years (Insel et al., 2006; McCurry, 2019; Stoehr et al., 2008). Evaluating the relationship between self-management behaviors like medication adherence and executive function in heart recipients may improve interventions designed to support the heart transplant patient.
The proposed dissertation research seeks to examine the relationships between executive function, cognitive impairment, illness representations, cerebral hypoxic injury mechanisms and medication adherence among heart transplant recipients. The purpose of this study is to increase knowledge about these relationships, with the goal of expanding insights into factors associated with non-adherence to immunosuppression following heart transplantation. This knowledge has the potential to inform the development of interventions to improve adherence. A descriptive, cross-sectional design will be employed, with measures conducted via telephone to mitigate risk to participants.
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