HIV in Canada: A primer for service providers
The HIV treatment cascade
- The treatment cascade reflects the different services someone living with HIV needs to achieve optimal health outcomes.
- The treatment cascade is based on the successive steps that are needed for a person living with HIV to achieve an undetectable viral load.
- There are no national estimates of engagement in the HIV treatment cascade for Canada.
The treatment cascade reflects the different services someone living with HIV needs to achieve optimal health outcomes, including HIV testing and diagnosis, linkage to appropriate medical care (and other health services), support while in care, access to HIV treatment if and when the individual is ready, and support on treatment. While enhanced engagement in the cascade may have a secondary benefit of reducing HIV transmission, the HIV treatment cascade does not include services for people who are HIV negative; these services are an additional component of an integrated framework.
The HIV treatment cascade has emerged as a convenient tool for assessing integrated health service delivery for people living with HIV. It is based on the successive steps that are needed for a person living with HIV to achieve an undetectable viral load. Research shows that people living with HIV who have an undetectable viral load are more likely to live long, healthy lives and are less likely to pass HIV to others. Starting from the total number of people living with HIV in a specific region (both diagnosed and undiagnosed), the successive indicators in the stages of engagement in the HIV treatment cascade are:
- total number of people living with HIV
- number of people diagnosed with HIV
- number of people linked to HIV care
- number of people retained in care
- number of people on HIV treatment
- number of people with undetectable viral load
At each stage of the cascade people may be lost to engagement and care as a result of many types of barriers, such as poor access to services; stigma and discrimination; poverty, food security and homelessness; and mental health and addictions issues. Typically only a small proportion of people living with HIV are engaged in all the steps needed to achieve an undetectable viral load. There are no national estimates of engagement in the HIV treatment cascade for Canada. In British Columbia it is estimated that 35% of people living with HIV in 2011 had made it through all of the steps in the cascade and achieved an undetectable viral load.
In a strategic discussion paper released in 2014, UNAIDS used the HIV treatment cascade to propose that by 2020:
- 90% of all people living with HIV will know their status;
- 90% of all people with diagnosed HIV infection will receive sustained ART;
- 90% of all people receiving ART will have viral suppression (undetectable viral load).
The strategy is informally known as “90-90-90”, and if these targets are achieved, 81% of all people living with HIV will be on treatment and 73% will have an undetectable viral load – the key indicator of ongoing successful treatment—and, therefore, be significantly less likely to transmit the virus to others.” Modelling studies show that achieving these targets would result in the end of the epidemic spread of HIV by 2030.
In 2015, Canada endorsed the 90-90-90 targets. Still, there are no national estimates of engagement in the HIV treatment cascade for Canada. In British Columbia it is estimated that 35% of people living with HIV in 2011 were engaged in care and support and had an undetectable viral load. In Ontario it is estimated that between 27% and 40% of people living with HIV between 2007 and 2012 were engaged in care and support and had an undetectable viral load.
The HIV treatment cascade – patching the leaks to improve HIV prevention – Prevention in Focus
Changing the narrative: Why HIV prevention in Canada needs to embrace HIV treatment –Prevention in Focus
The Engagement Cascade – The Positive Side
- Hull MW, Wu Z, Montaner JSG. Optimizing the engagement of care cascade. Current Opinion in HIV and AIDS. 2012 Nov;7(6):579–86.
- Gardner EM, McLees MP, Steiner JF, et al. The spectrum of engagement in HIV care and its relevance to test-and-treat strategies for prevention of HIV infection. Clinical Infectious Diseases. 2011 Mar 1;52(6):793–800.
- Vital signs: HIV prevention through care and treatment--United States. Morbidity and Mortality Weekly Report. 2011 Dec 2;60(47):1618–23.
- Wilton J. The HIV treatment cascade – patching the leaks to improve HIV prevention. Prevention in Focus. CATIE, Spring 2013. Available from: http://www.catie.ca/en/pif/spring-2013/hiv-treatment-cascade-patching-leaks-improve-hiv-prevention.
- UNAIDS. 90-90-90: An ambitious treatment target to help end the AIDS epidemic. 2014. Available from: http://www.unaids.org/sites/default/files/media_asset/90-90-90_en_0.pdf
- Nosyk B, Montaner JSG, Colley G et al. The cascade of HIV care in British Columbia, Canada, 1996-2011: a population-based retrospective cohort study. Lancet Infectious Diseases. 2014 Jan;14(1):40–9.
- Gilbert M, Gardner S, Murray J, et al. Quantifying the HIV care cascade in Ontario: Challenges and future directions. Poster presented at: 24th Annual Canadian Conference on HIV/AIDS Research, 30 May 2015; Toronto. Available from: http://www.cahr-acrv.ca/wp-content/uploads/2012/10/InfDis_26_SB_MarApr2015_Final.pdf