Technical Notes: Priority populations

Positive HIV tests and first-time HIV diagnoses are assigned (where applicable) to one or more of the priority populations outlined in Ontario’s Provincial HIV/AIDS Strategy. These populations are not mutually exclusive, and individuals can be classified as belonging to more than one priority population. In 2019, approximately 77% of positive HIV tests belonged to at least one priority population (GBMSM, PWID, ACB, Indigenous or Women). Approximately 27% of positive HIV tests belonged to two or more priority populations at one time. Approximately 75% of first-time HIV diagnoses belonged to at least one priority population. Approximately 23% of first-time HIV diagnoses belonged to two or more priority populations at one time.

Each population is uniquely defined by indicators of HIV risk factors, race/ethnicity, country of birth, and/or sex on the HIV test requisition and LEP forms. Where the defining criteria of each priority population is reported, HIV diagnoses are assigned to a priority population, where applicable. Assignment to these populations is based on information from the HIV test requisition forms and LEP forms, as follows:

  • Gay, bisexual and other men who have sex with men (GBMSM)
    • Sex is male or transgender male, and sexual contact with men reported as an HIV risk factor
  • People who are African, Caribbean, or Black (ACB)
    • Country of birth is an African or Caribbean country and/or race/ethnicity is Black
  • People who use injection drugs (PWID)
    • Injection drug use (IDU) reported as an HIV risk factor
  • Indigenous Peoples
    • Race/ethnicity is First nations or Inuit or Métis
  • Women (instead of Women*, see below)
    • Sex is female or transgender female

Women* is the official priority population as outlined in Ontario’s Provincial HIV/AIDS Strategy; it includes ACB women, women who use injection drugs, Indigenous women, transgender women, other women who face systemic and social inequities, and women who are more likely to be exposed to HIV through a sexual or drug using partner. As indicators of systemic and social inequities of HIV are not available in the HIV surveillance data, the priority population Women* is unable to be defined. Instead, OHESI uses “Women”, which is inclusive of all females and transgender women.

Information on HIV diagnoses by priority population is available for different years based on the priority population. Historically, the HIV test requisition form has obtained information on HIV risk factor and sex. Therefore, the GBMSM, PWID and Women priority populations are able to be assigned (if appropriate) from 1985 onward. Information on race/ethnicity and country of birth were added to the LEP form in 2009. Therefore, the ACB and Indigenous priority populations are only able to be assigned from 2009 onwards. The HIV test requisition underwent revision in 2018 to collect information on race/ethnicity and country of birth, and improve the documentation of transgender men and transgender women within HIV diagnosis data. Additional information on the revised HIV test requisition form is used to help assign priority populations (but not sex). These revisions will allow us to better characterize priority populations for both negative and positive tests. The high amount of missing information for positive HIV tests (approximately 34% on race/ethnicity and approximately 24% on exposure category between 2010 to 2019) means that information on priority population is missing for many diagnoses. Therefore, it may be more valid to focus on trends over time rather than the specific numbers or proportions.

To be assigned to any priority population, only information on that single priority population is required. For example, if race/ethnicity is missing but sex indicates male and HIV risk factors indicate sexual contact with men, the individual could be assigned to the GBMSM priority population. Assignment of priority population is excluded if data that defines that priority population is not reported.