Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science


Epidemiology and Biostatistics


Anderson, Kelly K

2nd Supervisor

Ali, Shehzad



People with psychotic disorders have long-term negative health outcomes and contribute large health system costs. Intervening among those at ultra-high risk (UHR) for psychosis may prevent or mitigate risk for psychotic disorder; however, it is unclear if we should treat all UHR individuals or only those above a certain risk threshold. The objectives were to systematically review the literature on the cost-effectiveness of UHR programs, and to conduct an economic evaluation of a risk stratification strategy, where treatment decisions are based on the probability of transitioning to psychotic disorder. Our systematic review found that UHR programs are potentially cost-effective. The economic evaluation found that only treating those at ≥20% risk to transition is cost saving to the Canadian health system, but returns worse health outcomes ($15,466 per quality-adjusted life-year), relative to treating all UHR individuals. Future research requires better valuation of cost and outcomes and trials examining risk stratification.

Summary for Lay Audience

Psychotic disorders are mental illnesses that have long-term negative consequences for a person’s functioning and quality of life, and are often expensive to treat and manage. Some studies have found that treating people at high risk for psychosis in specialized programs may be effective for slowing down progression to psychosis or preventing it entirely. Little is known about the cost-effectiveness of high risk programs compared to alternative treatment plans. Therefore, it is important to examine the cost-effectiveness of treating people in high risk programs to help inform future health policy decisions related to this population. The aim of this thesis was to review all available studies on the cost-effectiveness of high risk programs, and to then use this knowledge to inform the creation of an economic model to evaluate the potential benefit of prioritizing treatment to those at a much higher risk for psychosis (≥20% risk). In our review of prior economic studies comparing high risk programs to standard care, we found that high risk programs may provide value for money, but no conclusions can be drawn on what aspects of the treatment plan are cost-effective. Next, an economic evaluation was done to assess the Canadian health care system costs of only treating those at a very high risk for converting to psychosis (≥20% risk) based on a risk calculator compared to a standard ‘treat all’ strategy. Risk stratification has incremental costs of $15,466 to the health system per quality-adjusted life-year, compared to the other strategy. More specifically, our results show that risk stratification has potential to provide cost savings, but returns worse outcomes. This means that cost savings can occur only if health system decision-makers are willing to accept losses in health. Future economic evaluations would benefit from more rigorous methods of examining health care outcomes and costs associated with high risk programs. Future clinical trials that compare the effectiveness of personalized treatment plans to the standard of care may also help inform future economic models.

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