Dissertations & Theses (Open Access)

Date of Award


Degree Name

Doctor of Philosophy (PhD)


Trudy Millard Krause

Second Advisor

Robert Delgado

Third Advisor

Osama Mikhail


Background: Coronary artery bypass grafting (CABG) surgery and percutaneous coronary intervention (PCI) procedures have been associated with substantial financial costs in Texas. The annual hospital charges in 2016 for CABG surgeries and PCI procedures in Texas were $3.6 billion and $4.1 billion, respectively. Recently, these two procedures have become a target for bundled payment initiatives. Due to the lack of information about the demographics and variations associated with CABG and PCI episode payments for commercially insured patients, more research needs to be conducted to understand the magnitude of payments and the drivers of variation in payments in Texas. Objective: This study aimed to fill the gap by examining CABG and PCI medical costs through episode payment models. The first objective was to estimate both CABG and PCI episode payment variations in patient demographics for a large sample of the commercially insured population in Texas. The second objective was to examine the payment components that drive variability in 90-day episode payments across Texas. Methods: The study design was a retrospective cohort study of commercially insured patients 18 years of age and older undergoing CABG surgeries and PCI procedures in Texas regions for the years 2014 to 2018. Using Optum Clinformatics® DataMart (CDM): administrative claims data. For this study, the average 90-day episode payment for patients undergoing CABG surgeries and PCI procedures were first calculated and then assessed if there were wide demographic variations in the payments. The total 90-day payment was derived as the sum of the procedure and hospitalization payment and the payment associated with post-discharge utilization. All dollars were adjusted to 2018 values. Multiple linear regression models were used to identify factors impacting the 90-day total episode payments. After that, the variation in payments and the primary drivers of payment variations were identified. Hospitals and regions were divided into quartiles based on the mean episode payment for CABG surgeries and PCI procedures. Total episode payments were subdivided into five payment components (index procedure, professional services, post-acute care, readmission, and pharmacy) to investigate which components drove variability significantly by comparing them across high- and lowcost quartiles. Results: A total of 999 CABG episodes and a total of 2691 PCI episodes were identified. The mean (SD) 90-day episode payments at patient level for CABG surgeries and PCI procedures were $81,330 ($47,382) and $53,842 ($44,603), respectively. Certain patient factors, including age, patient region, comorbidities, type of insurance, length of stay, and readmission stage had effects on 90-day episode payments. The average 90-day payment at the hospital level in the highest- and in the lowest-payment quartiles ranged from $106,148 to $61,028, representing a difference of $45,121 (74%) for CABG surgeries. They ranged from $74,510 to $33,696, representing a difference of $40,814 (121%) for PCI procedures. The index procedure was the primary driver of 90-day CABG episode payment variation of 49%, while both the index procedure and the post-acute care were relatively similar sources of 90-day PCI episode payment variation of 37% and 36%, respectively. Conclusions: Payment variations existed widely in 90-day episode payments for commercially insured patients undergoing CABG surgeries and PCI procedures across Texas. Focusing on reducing readmissions and targeting the index payment component, which has contributed to a large proportion of episode payment variations, might be a potentially effective approach when developing initiatives to reduce CABG- and PCI-related costs and improve efficiency.