Electronic Thesis and Dissertation Repository

Thesis Format



Master of Science


Epidemiology and Biostatistics


Anderson, Kelly K.


Minimizing the duration of untreated psychosis in the first few years after illness onset is essential for improving prognosis for people with psychotic disorders. Leading up to the first onset of psychosis, many people experience early signs and symptoms, suggesting that there may be help-seeking or service utilization prior to first diagnosis. The family physician has been found to play a pivotal role in the pathways to care for people with first-episode psychosis. In this study, we used health administrative data from Ontario to construct a population-based retrospective cohort. These data were used to explore whether people with psychotic disorders had distinctive patterns of primary care service utilization in the six years preceding the first diagnosis of psychosis, relative to the general population comparison group matched on age, sex, and postal code. Our findings suggest that people with psychosis contact primary care over twice as frequently during the six years leading up to first diagnosis, relative to the general population. They have higher contact frequency across nearly all conditions, including mental health, physical conditions, and preventative health-related contacts. We also used Latent Class Growth Modelling to identify three distinct service utilization profiles: low, medium, and high-increasing usage, and we used negative binomial models to identify characteristics associated with each trajectory. Findings from this study can help inform initiatives to support Canadian family physicians and improve detection of early psychosis in primary care, which has implications for improved social, educational, and professional development in young people with first-episode psychosis.

Summary for Lay Audience

It is important for people who are experiencing psychosis to receive appropriate treatment as soon as possible. Before the start of psychosis, people may experience changes in their normal behaviour that may lead to a visit with a family physician. The family physician will record the patient’s symptoms for each visit, which may contribute to a final diagnosis later. If a family physician can recognize specific symptoms and diagnose a patient with psychosis sooner, that patient will receive appropriate treatment faster. However, not much is currently known about how people with psychosis seek help from family physicians. We will use Ontario Health Insurance Plan (OHIP) data to look at how family physician use differs between people who are diagnosed with psychosis and the general population during the time before the start of psychosis. We found that people with psychosis visit a family physician over twice as much as the general population before the start of psychosis. We also found that they visit family physicians for all health conditions, including mental health, physical health and preventative health visits. We also used a statistical technique that identifies distinct subgroups of people with psychosis following a similar pattern in the number of visits to a family physician over time. We found three subgroups: low, medium, and high-increasing number of visits to a family physician. It is important to study these patterns of family physician use in order to improve family physicians’ recognition and diagnosis of psychosis so that people with psychosis can get appropriate treatment sooner. Receiving appropriate treatment sooner is important for reducing the burden on people with psychosis. The start of psychosis usually happens during adolescence and young adulthood, which overlaps with major life and developmental changes. Receiving appropriate treatment sooner means that people with psychosis will have improved social, educational, and professional development.