Participants completed a nationally harmonized baseline questionnaire collecting social and economic demographics, personal and family health histories, medications, sleep patterns, alcohol and tobacco use, physical activity and environmental exposures. Regular follow-up questionnaires have been conducted to track changes in health, along with ad hoc questionnaires focusing on occupational history and impacts of the COVID-19 pandemic. Almost all participants (89%) can be linked with their administrative data such as the Ontario Cancer Registry. Data linkage opportunities with ICES, Ontario Health (Cancer Care Ontario) and CANUE are available.

Data from the following questionnaires are now available:

• OHS Baseline Questionnaire
• OHS Follow-up Questionnaire
• OHS and CanPath COVID-19 Questionnaire

Non-fasting blood samples were collected from more than 40,000 participants. A subset of this group, approximately 12,600 and 13,400 participants respectively, provided urine samples and physical measures.

OHS Dataset and BioBank

Learn more about the data and samples available to researchers here.

The OHS is one of six participating cohorts of the Canadian Partnership for Tomorrow’s Health (CanPath), alongside the B.C. Generations Project, Alberta’s Tomorrow Project, the Manitoba Tomorrow Project, CARTaGENE in Quebec and the Atlantic PATH. CanPath is also supporting the formation of a seventh cohort in Saskatchewan to expand the depth of CanPath’s national dataset and biological assets. CanPath is studying the biology, behaviours and environments of Canadians to learn more about the causes of chronic disease and cancer for a healthier Canada and world. To date, CanPath has collected data from over 330,000 Canadians. CanPath’s data and biosamples are available to researchers through the CanPath Portal.

Researchers are invited to apply to access Ontario Health Study data and biosamples to find ways to better treat and prevent cancer and chronic disease