Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Epidemiology and Biostatistics


John-Baptiste, Ava

2nd Supervisor

Lizotte, Daniel



Introduction: The relationship between patient demographics, clinical factors, and cost of coronary artery bypass graft (CABG) is complex. Investigation of these relationships is important to aid clinical practice and inform reimbursement models. This thesis analyzes multiple different domains in order to understand the significant factors that impact the cost of CABG at the London Health Sciences Centre (LHSC).

Methods: Model selection, construction of nested descriptive models, exploration of mediation analysis of the impact of peri-operative factors and cost through length of stay, and construction of estimative models were performed.

Results: Several baseline characteristics, socio-demographics, peri-operative variables, and post-operative variables were found to be significant drivers of cost. Some of these include having dementia upon admission, experiencing major complications, and having longer length of stay.

Discussion: Through analysis of multiple domains, we begin to develop an understanding of the significant factors that impact the cost of CABG procedures at the LHSC.

Summary for Lay Audience

At the London Health Sciences Centre (LHSC), around 850 coronary artery bypass graft (CABG) procedures are performed annually. CABG surgery involves grafting (sewing) vessels onto the arteries that supply blood to the heart to relieve narrowing of those arteries, a condition known as coronary artery disease. CABG surgery relieves coronary artery disease symptoms, which include pain, weakness and fatigue, and reduces the rate of death from coronary artery disease. Cardiac surgeons and hospital administrators are concerned the reimbursement for each CABG procedure provided by the Ontario Ministry of Health and Long-Term does not cover the actual cost of surgery, particularly for more complicated cases. Through analyses of hospital datasets, this thesis identified several significant drivers of cost. Some of these factors include having dementia upon admission to the hospital, experiencing major complications, and length of stay. We also performed analyses that showed that the relationship between these variables and costs are quite complex. We found that certain factors like major complications was not only associated with increased costs directly, but also increased the length of stay at the hospital. This increase in length of stay results in additional increased costs. We also showed that there were several variables that were very important in estimating the cost of CABG at the LHSC that were not accounted for by the models that are currently used to inform reimbursement of these procedures.