Positive HIV tests represent unique individuals and include first-time HIV diagnoses and people with previous evidence of HIV. Previous evidence of HIV includes having been diagnosed with HIV previously outside Ontario, or having linked previous HIV viral load testing.
The exposure category is meant to represent an individual’s most likely means of HIV acquisition. The exposure categories are mutually exclusive. When more than one risk factor is reported for a single individual, a hierarchy is used to assign an HIV test to a single exposure category.
HIV is not a generalized epidemic in Ontario. It is concentrated in a small number of populations that have higher HIV prevalence than the general population: known as “priority populations” for HIV programming in Ontario’s response to HIV. Each population is uniquely defined by indicators of HIV risk factors, race/ethnicity, country of birth, and/or sex. These populations are not mutually exclusive, meaning an individual can be in more than one priority population.
OHESI uses laboratory data on HIV-positive diagnostic tests from the Public Health Ontario (PHO) Laboratory along with information documented by ordering providers on test requisition forms and from the LEP. OHESI does not use information from the integrated Public Health Information System (iPHIS), the electronic, web-based system used by PHUs for case-management and reporting to the Ontario Ministry of Health on diseases of public health significance, including HIV.
Individuals who receive an HIV diagnostic test are assigned to a geographic region based on their residence or, if not reported, the address of the ordering provider. Health regions are groupings of public health units that are used for HIV program and service planning and in surveillance reports.
Data on this website come from the Public Health Ontario (PHO) Laboratory, which conducts centralized HIV diagnostic testing for the province. OHESI uses additional data sources as needed, including Statistics Canada data for population estimates and estimates on pregnancy from the Better Outcomes Registry & Network (BORN).
The HIV care cascade is a framework to understand how people are diagnosed with HIV, linked to care, engage in treatment and achieve viral supression. Each indicator requires a specific definition in order to obtain an accurate estimate for each step in the cascade.