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Explore the Study’s Data and Biosample Holdings

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Questionnaire Data

Questionnaire data from six OHS data collection activities are available: the Baseline Questionnaire, including the Pilot Questionnaire; a Follow-up Questionnaire; the Work History Questionnaire; the COVID-19 Questionnaire; and the COVID-19 Antibody Study.


Timeline of Questionnaires:


Information on data linkage opportunities can be found here.

Many questionnaire variables have been collected at up to four timepoints. Click here to view a summary of questionnaire data.


OHS Questionnaires:

  • The Baseline Questionnaire was completed by ~225,000 participants. Two versions of the questionnaire were used: Baseline 1, completed by 196,215 participants, and Baseline 2, completed by 22,509 participants.
  • The Baseline questionnaire included almost 1,400 variables covering: social and economic demographics personal and family health histories including medications; lifestyle behaviours such as sleep patterns, physical activity and alcohol and tobacco use; environmental exposures.
  • The Follow-up questionnaire was completed by ~47,100 participants. The questionnaire collected an update on participants’ health and behaviours, as well as new variables on e-cigarette and cannabis/marijuana use.
  • The Work History Questionnaire was completed by ~33,600 participants. This questionnaire collected data on participants’ occupational histories, such as job information, commute characteristics, occupational exposures, and psychosocial environment.
  • The COVID-19 Questionnaire was completed by ~42,000 participants. This questionnaire focused on participants’ exposures, symptoms and diagnosis of COVID-19 since March 2020, and social, economic, psychological, and emotional impacts. Updated personal medical history, lifestyle behaviours, and anthropometrics were also collected.
  • The COVID-19 Antibody Study collected questionnaire data and a blood spot sample from ~10,000 participants at up to three timepoints. The questionnaires covered participants’ exposures, symptoms and diagnosis of COVID-19, healthcare use related to COVID-19, COVID-19 vaccination and side effects, lifestyle risk factors such as smoking, and psychological and emotional impacts. Variables on Long COVID were collected in the third timepoint.

  • Regular follow-up questionnaires will be conducted to track changes in overall health.

  • Data linkage opportunities are available through ICES, Ontario Health, CANUE, and other repositories. Data for 83% of participants have been linked with administrative health records, such as the Ontario Cancer Registry or OHIP claims databases.


Questionnaire Data From Other Sources

  • ~3,000 participants also participated in the Canadian Alliance for Healthy Hearts and Minds (CAHHM) Study from 2014-2017. To accompany imaging data, a questionnaire collected variables on diet, physical activity, health services use, perception of community factors on health, immigration and acculturation, and cognitive function.

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