Semester

Fall

Date of Graduation

2018

Document Type

Dissertation

Degree Type

PhD

College

School of Pharmacy

Department

Pharmaceutical Systems and Policy

Committee Chair

S. Suresh Madhavan

Committee Co-Chair

Xi Tan

Committee Member

Usha Sambamoorthi

Committee Member

Charles Ponte

Committee Member

Geroge A. Kelley

Abstract

Hypertension and type-2 diabetes mellitus (T2DM) are among the most prevalent chronic conditions that often co-exist. Their co-existence increases the risk for comorbidities due to their impact on other organs such as blood vessels (leading to vasoconstriction/hypertension); brain (resulting in increased caloric intake); pancreas (decreased in beta-cell mass and glucose sensing); bone (possibly decreasing bone mass and strength). Occurrence of comorbidities can complicate the already complex care of diabetes and hypertension. It increases the risk of poor patient outcomes such as preventable hospitalization, adverse drug events and mortality. However, different comorbidities can affect the co-management differently. We identified the types of comorbidities based on Piette and Kerr framework as, concordant (condition that share pathophysiology or treatment plans with T2DM and hypertension, such as cardiovascular disease and chronic kidney disease), discordant (conditions that are not directly related either by pathophysiology or disease management, such as depression osteoarthritis and chronic pulmonary obstructive disease), and dominant (conditions that are so grave and complicated that their care takes precedence over the care of other health problems, such as cancer, end stage liver disease and retinopathy). Numerous studies have evaluated the impact of number of chronic conditions on T2DM management as well as hypertension management. However, there is a scarcity of literature on the impact of type of comorbidities on T2DM and hypertension co-management. Therefore, the aims of this dissertation were to evaluate (1) the association between the type of co-existing chronic condition (concordant or discordant) and self-care behaviors among adults with T2DM and hypertension, (2) the impact of the type of incident comorbid chronic conditions on medication adherence before and after the diagnosis of comorbidity among working-age adults with diabetes and hypertension, and, (3) the relative increase in total healthcare expenditures associated with the type of comorbid condition among commercially insured working-age adults with diabetes and hypertension. A retrospective cross-sectional study design with data from 1,998 individuals aged 18 years or above from 2009-2014 National Health and Nutrition Examination Survey (NHANES) was used to accomplish aim (1). For aim (2) and (3) we used a retrospective longitudinal cohort study design among a working age (18-63 years) sample of commercially insured adults with T2DM and hypertension with at least one prescription medicine for both diabetes and hypertension. We identified patients with both T2DM and hypertension and a prescription for oral hypoglycemic medicine (OHM) and anti-hypertensive medicine (AHM) during the 12 months’ baseline period. Patients must not have any comorbidity during the baseline period. Our final study sample included 10,544 commercially insured adults. We observed a statistically significant difference in all self-care behaviors except healthy-eating by the type of comorbid condition. Adults with discordant conditions were less likely to self-monitor glucose levels (OR = 0.53, 95% CI=0.76) and blood-pressure (OR = 0.40, 95% CI = 0.24, 0.68). Medication adherence to OHM and AHM increased following the incidence of comorbidity. It was highest among those who developed a discordant condition (AOR = 1.44, 95% CI = 1.28, 1.60); followed by those who developed a concordant condition were (AOR = 1.43, 95% CI = 1.19, 1.66); and those who developed a dominant

condition (AOR = 1.30, 95% CI = 1.14, 1.46). The results of aim (3) indicate that the average total healthcare expenditures for our study sample were $12,165. The highest increase was observed among T2DM and hypertension patients who were diagnosed with a dominant condition ($8,763), followed by patients with a concordant condition ($8,537), and lastly those with a discordant condition ($2005). In summary, the results of our study indicate that the Piette and Kerr classification of comorbidities only worked in explaining self-care behavior, whereas medication adherence and healthcare expenditures increased irrespective of the types of comorbidity.

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