Treatment Choice in Urea Cycle Disorders: How Healthcare Access Contributes to the Decision to Continue Medical Management or Pursue Liver Transplant Open Access
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Rare diseases impact approximately 25 million individuals in the U.S. and Canada combined and represent a major challenge for the health services community. Despite this, rare diseases are rarely examined within fields of public health or health service research. Inborn errors of metabolism represent one key group of rare disorders with a high prevalence of disability and death. Urea Cycle Disorders (UCD) are a group of eight rare inherited disorders of metabolism characterized by deficiencies in ammonia detoxification and urea synthesis – a process in the liver that converts otherwise toxic ammonia into urea for excretion in the urine. When this mechanism does not function properly, it can result in hyperammonemia, which can lead to early and recurrent brain damage or death. Pharmaceutical drugs in combination with highly controlled and restrictive low-protein diets and metabolic formulas are used to manage patients with UCD. Medications and restricted diets do not completely remove the risk of hyperammonemia in patients with UCD and many patients treated conservatively through these methods have still been reported to suffer from acute episodes of hyperammonemia. Thus, an increasing number of patients with UCD have been undergoing liver transplantation as a procedure that “cures” the hyperammonemia. However, liver transplantation is a complicated surgical procedure, which carries significant risk of both mortality and morbidity and requires a life-long regimen of medication management to avoid organ rejection. Patients, families and their providers are therefore facing a difficult dilemma. Should the patient be managed conservatively with diet and medications or undergo a liver transplant? Families affected by rare conditions like UCD are also presented with unique and complex challenges related to the cost, coverage, and availability of sub-specialized care, which further complicates treatment decision-making. UCD patients require sub-specialized healthcare management not available through primary care, smaller specialty practices, or community hospitals, raising questions about how the regionalization of major UCD treatment influences access among this population and as an extension, treatment choice. Variation in public and private coverage policy, narrow networks, high treatment costs, benefit denials and appeals, and fragmented financial aid programs have also been anecdotally identified as barriers to affordable treatment for UCD and other rare conditions. This dissertation research project explores treatment decision-making in families affected by UCD, examining health care access as a key driver of the choice between medical management (MM) and liver transplant (LT). It accomplishes this through three separate but related studies. The first study utilized grounded theory to construct a conceptual framework that describes the treatment decision making experience of parents whose children are diagnosed with UCD. The framework outlines the clinical, personal, social, and system factors that drive the decision between MM and LT and describes the circumstances that frame families’ personal perceptions of risks and benefits as well as the context within which decisions about treatment are made. Findings from this study equip providers with evidence upon which to improve their approach to treatment counseling and guidance. The study also identified access to sub-specialized medical care as a key dimension of treatment choice. It concluded, that among other factors, issues related to the availability, delivery, and coverage of UCD care all have implications for treatment decision-making thus, providing a basis for the inquiries examined through the subsequent two studies within this dissertation. The second study utilized GIS methodology and regression analysis to examine the association between proximity to high-quality sub-specialized metabolic and/or liver transplant care and treatment. This analysis did not establish a statistically significant relationship between proximity (i.e., geographic access) to any high-quality care center and treatment choice (i.e., MM vs. LT) but did establish a strong, statistically significant relationship between treatment status and geographic access to certain transplant centers known in the community for their support of and excellence in transplant for UCD. The study found that patients who live nearest to these transplant sites were three to four times more likely to undergo a liver transplant than those who live in nearest proximity to one of the other transplant centers included in the analysis. These findings demonstrate the existence of inter-institutional variations in practice around treatment for UCD and raise questions about the impact of these variations on equitable access to care within the UCD community and as a consequence of this, treatment choice. The third study examined cost and coverage of care for UCD through the collection and analysis of primary survey data from patients and parents affected by the disorder. Findings highlighted high out of pocket costs and pervasive barriers to coverage across service categories related to the management of UCD including access to supplements, medical foods and formula, medications, routine consultative care, emergency medical care, and medical travel. The study also noted substantial differences in out of pocket cost and coverage experience by treatment and insurance type. Study results indicated higher out of pocket spending and more frequently reported coverage concerns under medical management than under liver transplant and among privately insured respondents when compared to Medicaid recipients. Finally, this third study highlighted the financial hardships experienced by families affected by UCD as a consequence of caring and paying for the care of a child with special health care needs. This included barriers to career development and the direct financial implications of high medical bills like credit card debt, lost savings, and even challenges paying for basic necessities like food and rent. Together, the three studies conducted as part of this dissertation apply mixed methods research to identify and explore important health services related challenges associated with treatment choice in UCD and contribute evidence to an otherwise under-developed area of research.