Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article


Master of Science


Epidemiology and Biostatistics


Ali, Shehzad

2nd Supervisor

John-Baptiste, Ava



Colorectal cancer (CRC) screening uptake may be associated with social determinants of health and could indicate potential barriers to health service access. The goal of this thesis was to evaluate the association of social determinants with CRC screening in screen-eligible adults. We used Andersen’s Behavioural Model of Health Service Utilization and the PROGRESS-Plus Framework to conceptualize potential social determinants. Our first study was a systematic review of peer-reviewed Canadian studies, and the second was a cross-sectional analysis of data from the Canadian Longitudinal Study on Aging (CLSA). The systematic review found lower uptake was associated with non-White ethno-racial identity, less than post-secondary education, and low income. The cross-sectional analysis found lower odds of uptake for younger age, female sex, lower income, partial retirement, no recent contact with a family physician, and fair self-rated general health. We recommend future research on the role of tailored interventions to address disparities in uptake.

Summary for Lay Audience

Preventive health, including regular check-ups, patient counselling, and periodic disease screening, is a cornerstone of general medical practice worldwide. Early detection of disease can improve the potential effectiveness of treatment and reduce cancer-related mortality. One area in which preventative medicine has demonstrated success is in the early detection of colorectal cancer (CRC). CRC develops in the colon (also known as the large intestine) or rectum and is characterized by uninhibited growth of cells.

In Canada, provincial health insurance programs provide several screening tests for CRC that can help adults aged 50-74 years detect the disease before developing symptoms. Despite their wide availability, the use of CRC screening is not distributed equally across Canada. Members of certain socioeconomic groups may face barriers to accessing healthcare services resulting in reduced uptake of routine screening tests. Reduced uptake of screening could result in thousands of undetected, treatable CRC cases lowering quality of life and life expectancy in the population. It is important to identify the characteristics associated with lower screening use, so that future policies and programs can be developed to reduce disparities among eligible adults. Therefore, this integrated thesis aimed to identify social factors associated with reduced uptake of CRC underscreening in Canada.

We conducted a systematic review of the literature and summarized findings from previously published Canadian studies. We found that non-White ethno-racial identity, lower income, and less than a post-secondary education were associated with lower screening. We analyzed data from the Canadian Longitudinal Study on Aging and found that those with younger age, female sex, lower income, and partial retirement status were less likely to have been screened for CRC. We also found a connection between screening uptake and participants having recently been to a family physician or living in a province with an established provincial screening program. In conclusion, eligible Canadians with certain sociodemographic characteristics were more likely to be underscreened than others. Future research should examine the effect of community outreach, focused health promotion activities, and personalized reminders in increasing uptake among individuals in these groups.