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How understanding testing patterns can inform recommendations for HIV testing
Sep 5, 2014 by Mark Gilbert, Physician Epidemiologist, Clinical Prevention Services, BCCDC
Populations with a higher prevalence of HIV infection, such as gay, bisexual or other men who have sex with men (MSM) or people who use injection drugs (IDU), are often recommended to get an HIV test at least once a year. Many countries recommend more frequent HIV testing for people at ongoing risk, ranging from every 3 to 6 months, or without specifying a time period.
As part of the STOP HIV/AIDS pilot project, we looked at the prior HIV testing patterns for people with a new HIV diagnosis, to see how long it had been since their last HIV test (called the inter-test interval, or ITI). As these individuals are clearly at the highest risk of infection, we thought this study may help to inform recommendations for how often people at ongoing risk should be tested.
Summary of evidence
Of the 2004 new HIV diagnoses in the provincial surveillance system, between 2006 and 2011, 44.3% did not have a previous negative HIV test recorded.
Of those with a prior negative HIV test, the inter-test interval was skewed, with 50% of people (the median) having an ITI of 20 months or less. The pattern differed by group (Figure 1), with MSM having the shortest median ITI (15 months), followed by IDU (21 months) and people who acquired HIV through heterosexual sex (> 30 months).
41% of MSM and 33% of IDU had a previous negative test that was a year ago or less. Having a longer ITI was more likely for MSM and IDU who were older, and lived outside of the Vancouver area.
Figure 1: Time since last negative HIV test (inter-test interval) among MSM, IDU and heterosexual persons at the time fo their HIV diagnosis, BC, 2006-2011.
Implications for practice
Fewer than half of MSM and IDU with a new HIV diagnosis had a recorded negative HIV test in the past year. If the overall frequency of testing were to increase in these populations, HIV diagnoses may occur at an earlier stage. Earlier diagnosis, along with treatment, leads to improved health outcomes, as well as opportunities for preventing passing HIV to partners.
When seeing clients who are male with male sex partners, or who have a history of use of injection drugs or sharing drug paraphernalia, it is important to offer HIV testing at least annually, and as often as every 3 to 6 months for clients who are at ongoing risk of infection.
The findings from this study led to the adoption of these testing recommendations by the STOP project, which are also included in the recently released HIV testing guidelines for BC.
Mark Gilbert, Travis S. Hottes, Richard Lester, Réka Gustafson, Mel Krajden, Gina Ogilvie. Time since last negative HIV test among men who have sex with men and people who use injection drugs in British Columbia, 2006-2011. Canadian Journal of Public Health, 2014;105(1):e63-68.
For a copy of this article please email smartsexresource(at)bccdc.ca
For more information
The HIV Testing Guidelines for the Province of British Columbia (2014) can be found at http://hivguide.ca
Categories: New knowledge