ABSTRACTLANNY S. INABNIT. Rural Versus Urban Differences in Hospital Readmissions, Inpatient Mortality, and Cost Among COPD Patients. (Under the direction of Dr. AHMED ARIF)Objectives: Chronic obstructive pulmonary disease (COPD) affects about 30 million people in the United States. Focusing on COPD, the aims of my dissertation were to identify factors that impacted 30-day readmissions (article 1), inpatient mortality (article 2), and costs of care (article 3). Comorbidities were analyzed to determine their effects on all outcomes. I also assessed differences in nonmetropolitan (rural) and urban (metropolitan) areas of residence for all outcomes. Methods: I used data from the 2016 Nationwide Readmission Database (NRD) for articles 1 and 3 and the 2016 National (Nationwide) Inpatient Sample (NIS) database for article 2. I used: descriptive statistics to report mean (standard deviation) for continuous variables, the Chi-square test for categorical variables was used for mortality, and unadjusted and multiple logistic regression was used for odds ratios. The generalized linear model (GLM) was used for the adjusted analysis of total average cost and margins command was used to determine differences in total average cost. Comorbidities were assessed using the Elixhauser Comorbidities software. Nonmetropolitan status was used as an interaction term to determine if differences occurred between nonmetropolitan and metropolitan areas of residence. Results: In article 1, I found that patients living in metropolitan areas had higher 30-day readmission rates. Patients with a length of stay greater than 4 days had a 24% increase in readmission rates. Males were more likely to be readmitted than females. Patients living in nonmetropolitan areas who received Worker’s Compensation, or were enrolled in CHAMPUS, CHAMPVA, and other governmental programs had a higher readmission rate. Patients with COPD in nonmetropolitan areas with cardiac arrhythmias, solid tumor without metastasis, pulmonary circulation disorders, and peripheral vascular disorders had higher odds of readmission as compared to patients with COPD in metropolitan areas. In article 2, patients who were 75+ had 3 times higher odds of inpatient mortality than those 40-54. Males had an 18% increase in odds of mortality compared to females. Patients with Medicaid, private insurance, Worker’s Compensation, CHAMPUS, CHAMPVA had higher odds of mortality than those with Medicare. Being admitted to a large hospital was associated with increased mortality compared to being admitted to a small hospital. The odds of inpatient mortality differed by rural or urban residence if the patient also had metastatic cancer, pulmonary circulation disorders, or fluid and electrolyte imbalance. In article 3, patients with a length of stay of 4 or more days had higher costs of care regardless of residence. Patients from nonmetropolitan areas in the three highest household income categories had higher costs compared to those living in metropolitan areas. Readmission within 30 days was associated with higher total costs for patients from nonmetropolitan and metropolitan areas. Patients who also had congestive heart failure and uncomplicated hypertension who lived in nonmetropolitan areas had higher costs. Patients living in nonmetropolitan areas who had coagulopathy had higher costs. Discussion: I examined three outcomes that have the largest impact on the health of patients diagnosed with COPD. It would be useful to use future years of the NRD and NIS to determine if the outcomes found in this dissertation exist or if there is a shift to new variables that are impacting outcomes. It will be especially useful to examine the effects that COVID-19 has had on outcomes for patients with COPD.