Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science


Epidemiology and Biostatistics


Sarma, Sisira

2nd Supervisor

Zaric, Greg



This study assessed cost-effectiveness of pharmacogenomics (PGx)-based azathioprine (AZA) compared to standard AZA therapy for ulcerative colitis (UC) patients in Canada. A patient-level Microsimulation model was developed to compare the lifetime costs and quality-adjusted life years (QALYs) gained by a hypothetical cohort of UC patients with age and sex characteristics. The parameters used in the model were derived from the published literature and costs from the Ontario Schedules of Payments and published sources. The results were summarized in terms of the incremental cost-effectiveness ratio (ICER). Compared to standard AZA, PGx-based AZA care was the dominant strategy with 0.17 incremental QALYs and cost savings of CAD$2,724. The probabilistic sensitivity analysis showed that PGx-based AZA had greater probability of being cost-effective compared to standard AZA at any willingness to pay (WTP) threshold. At a WTP threshold of $50,000/QALY, PGx-based AZA was the cost-effective treatment in 97% of the iterations, while standard AZA cost-effective strategy in 3% of the iterations. We found that PGx-based AZA care presents good value for money and has a higher probability of being cost-effective for UC patients in Canada at a WTP threshold of $50,000/QALY.

Summary for Lay Audience

Ulcerative colitis (UC) is one of the two most common forms of inflammatory bowel disease (IBD) along with the Crohn’s disease. Patients with UC have been commonly treated by a drug called azathioprine (AZA) to maintain the clinical remission. Although AZA is a well-established therapy in the treatment of UC, it is also associated with a variety of adverse drug reactions (ADRs) such as bone marrow suppression, gastrointestinal disturbances, flu-like illness, hepatotoxicity, pancreatitis. Rigorous blood monitoring of the patients treated with AZA is required to avoid adverse events like bone marrow suppression. AZA-related adverse events entail a substantial burden on patients’ health and the healthcare system. In comparison, pharmacogenomic-based (PGx) AZA therapy adjusts the drug dose according to the inherent genetic differences of UC patients and has been shown to reduce the risk of adverse events. However, PGx-based AZA entails an upfront cost for genetic testing to identify patients who are likely to develop AZA-induced ADRs. This cost-effectiveness analysis compares the lifetime costs and benefits incurred under PGx-based AZA care and standard AZA treatment. We found that PGx-based AZA care improved the health of UC patients by reducing the risk of ADRs as compared to standard AZA. Moreover, we also found that PGx-based AZA care reduced the overall cost of caring UC patients.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 4.0 License.

Available for download on Sunday, December 31, 2023