What is the OCS?

Source population: people living with HIV who are in care in Ontario

Eligibility criteria:

  • Positive HIV-antibody test or other laboratory evidence of HIV infection
  • Patients at a participating OCS clinic
  • Aged 16 years or older
  • Capable of providing informed consent

Recruitment: Hospital-based specialty HIV clinics and primary care practices

The Ontario HIV Treatment Network Cohort Study (OCS) is a community-governed, province-wide research study aimed at improving the health and well-being of Ontarians living with HIV. Established in 1996, over 3,700 individuals actively participate at nine HIV clinics across the province. The OCS is the largest HIV cohort in Ontario and one of the largest in North America. It represents a diverse group of Ontarians living with HIV, including men and women of different ages, sexual orientations and ethnicities.

The OCS promotes clinical, psychosocial and socio-behavioural research to inform government policy, clinical practice and other care and support services. OCS team members work with leaders in the fields of HIV/AIDS, hepatitis C and other sexually transmitted and bloodborne infections.

A 2015 study assessing engagement in care among OCS participants between 2001 and 2011 found that 87% of participants were receiving regular viral load and CD4 tests; 77% were taking antiretroviral medication; and 76% had a suppressed viral load.



To develop and sustain a unique prospective cohort, governed by people living with HIV, and used to support collaborative, rigorous research in population health, clinical, psychosocial and behavioural sciences and health services research



Phase I


Phase II


Phase III