For people living with HIV, knowing your status is an important first step to accessing care and, when ready, treatment. Advances in our understanding of how antiretroviral treatment improves the long-term health of people living with HIV and how it reduces the risk of passing HIV to others has created a renewed resolve by many working in HIV to investigate ways to diagnose those living with HIV who don't know it (the undiagnosed). This is essential to ensure both the health and prevention benefits of antiretroviral treatment are optimized.
Using the recent example of the Seek and Treat for Optimal Prevention of HIV/AIDS (STOP) Project in Vancouver BC, this article will explore two approaches to diagnosing the undiagnosed: routine testing and targeted testing. For many working in HIV there are strong opinions on both sides. We look at how these strategies may be complementary to one another.
As of 2011, it was estimated that 25% of people living with HIV in Canada were not aware they were living with HIV (17,980 people).1 Furthermore, many people are being diagnosed later in their infection.2,3 In 2012 in Manitoba, for example, 41% of people had CD4 counts of fewer than 200 at the time of diagnosis.4 A study conducted between 1998 and 2003, predominantly among Aboriginal peoples, found that 28% of clients had a CD4 count of fewer than 200 at the time of diagnosis.5-7 These data suggest that current testing strategies are inadequate. It is essential that we address this gap because missed and late diagnoses have health and prevention implications.
Antiretroviral treatment (ART) has evolved dramatically since it first became available in 1996. Newer medications are more potent, less toxic and easier to take than ever before. We now know that early initiation of ART has benefits for both the long- and short-term health of people living with HIV. In addition, research shows that people living with HIV are much more likely to take significant steps to avoid passing on HIV once they know they have HIV.8,9
We have also learned that HIV testing has other implications for HIV prevention. Early diagnosis may help identify people in the early or acute stages of HIV infection, when prevention counselling can be particularly important. During acute HIV infection, people have higher amounts of virus in their bodily fluids making them more likely to pass HIV to their sexual partners. Early diagnosis can also identify more people who meet the guidelines for starting treatment. Successful treatment drastically reduces a person's viral load, which significantly decreases the likelihood that they will pass HIV to others. This means that if enough people living with HIV know their status, practice safer sex and begin treatment, there is a possibility to significantly reduce the number of new infections.
In Canada, our main testing approach has been targeted HIV testing -- one in which testing is conducted with people/populations identified as at high risk for exposure to HIV. Targeted testing can take two main forms: provider-initiated testing, where a healthcare provider identifies certain risk factors that prompt them to offer an HIV test to their patient, or client-initiated testing (sometimes called voluntary counselling and testing -- VCT),10 where individuals who feel they are at risk for HIV, or who believe they may have been exposed to HIV, seek out and request HIV testing.
There are many benefits to targeted testing approaches. Targeted testing provides a good opportunity for service providers to provide counselling to people from higher-risk populations, who test negative, about their HIV risk and how they can protect themselves in the future. Resources can also be specifically targeted for testing of communities most affected by HIV. This ensures that testing reaches those most at risk for HIV. Targeted testing approaches are less likely to result in patients being tested without their knowledge due to the pre- and post-test counselling procedures and the requirements for informed consent. Finally, these approaches do not rely on people accessing healthcare services; they can be tailored to delivery in a range of venues such as bathhouses and needle exchange sites.
One major barrier to the success of provider-initiated targeted testing is that it relies on the ability of a healthcare provider to identify risk factors for, or symptoms of, HIV. Healthcare providers may not be able to do this because risk factors or symptoms were not disclosed by the client or because the provider did not know what risk factors or symptoms should prompt them to offer an HIV test.11-13 In busy healthcare settings, a healthcare provider might decide not to offer an HIV test because they don't feel they have the time to conduct risk assessments (to figure out if a patient might be at risk for HIV) or pre- and post-test counselling.14 While building the capacity of healthcare providers to conduct targeted HIV testing is possible, its reliance on assessments and actions at the individual level (of either service providers or clients) makes it difficult for this strategy to be employed evenly and on a widespread basis.15
One major barrier to the success of client-initiated targeted testing is that it relies on a person's ability to understand and accept their risk of getting HIV.16 In other words, for client-initiated testing to work, an individual has to know what HIV infection is, understand how HIV is transmitted, evaluate their risk, and be able to ask for an HIV test, which some people don't do out of a fear of stigma and discrimination. Studies in both Canada and the U.S. have suggested that often people don't accurately assess their own risk and, therefore, don't seek out testing.17-19 Even if a client is able to adequately assess their risk for HIV infection, clients may be denied HIV testing by a healthcare provider. This can be due to a lack of knowledge about HIV transmission, because a client has not openly shared the sources of risk for HIV infection in their lives, or because the healthcare provider fears having to give their client an HIV-positive diagnosis.20
In the broadest sense, routine testing differs from targeted testing in that HIV testing is made a component of periodic routine medical care and that no assessment of risk for HIV is required for a test to be offered to the patient. Routine testing may mean offering to test every person in a particular setting or healthcare environment, such as a hospital emergency room or a family physician's office.
Routine HIV testing is already considered a best practice for pregnant women in Canada. In 2002, the Public Health Agency of Canada (PHAC) recommended routinely offering an HIV test to every pregnant woman in Canada.21-23 Every province and territory in Canada has a routine testing approach for pregnant women. This has led to a significant reduction in the number of infants who acquire HIV during pregnancy and childbirth.24
In 2006, the U.S. Centers for Disease Control (CDC) changed their HIV testing guidelines to recommend that HIV testing be conducted as a normal part of medical practice, similar to other treatable conditions.14 Canada followed suit in 2013 with PHAC developing a new HIV Screening and testing guide, which recommends that consideration and discussion of HIV testing be made a component of periodic routine medical care. However, since the direct delivery of most medical services is exclusively a provincial responsibility the impact of these guidelines on the routine offer of an HIV test is unknown.
Advocates for routine testing strategies argue that this blanketed approach to HIV testing is the "missing ingredient" that is required to identify the significant number of people living with HIV who have not yet received a diagnosis.3,25,26 They suggest that offering HIV testing routinely, regardless of a person's real or perceived risk of contracting HIV, will help avoid some of the challenges with targeted testing. Routine testing strategies could also increase HIV diagnoses for those people who access healthcare primarily through walk-in clinics or emergency rooms. They further suggest that making HIV testing a routine part of everyone's healthcare will help de-stigmatize HIV by normalizing HIV and HIV testing. Others argue that testing strategies that rely heavily on routine HIV testing may give the false impression that HIV affects everyone equally. However, some populations are disproportionately vulnerable to HIV transmission and, therefore, should receive the specific opportunities for prevention counselling that arise from targeted testing approaches.
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