HIV Testing and Monitoring the Epidemic

HIV Testing and Monitoring the Epidemic: New Tools for Patients and Populations. Session 51 Symposium

This was one of the conference’s last sessions and was very well attended.

HIV self-testing: Opportunities and Challenges. Abstract 162

Dr Julie Myers, New York City Department of Health

This was an important talk given that increased access to HIV point-of-care testing is one of the key aims of the Melbourne Declaration. It is worth watching on the CROI webcast.

Last year the FDA approved the Alere Determine HIV Combo home self-testing kit, also known as Orasure.

Dr Myers provided the results from a recent 5,000+ patient trial of the Orasure rapid HIV home testing kit, which was conducted across 20 sites in the USA.

These data were given to the FDA Advisory Committee last year by the product sponsor but have not yet been published.

In this study they found that 82% of people using the test were from high HIV prevalence areas.

5,055 patients were evaluable for test results. The overall prevalence was 2.12%. See slide below from Dr Myer’s talk for further results of this study.

Note that the sensitivity is only 91.67%. Of note when trained professionals use this test its sensitivity is over 98%. 

As we know this product went on to become licensed in the USA. Of note, people who use the kit have 24-hour phone access for support and for referral to sites for confirmatory testing.

There are few post marketing data available but there have been some published data to indicate that users of the test find it is ‘easy to use’.

How homebased self-testing tests are being used

Dr Myer then discussed the way that the tests are being used including by those who are at risk and by potential sexual partners. Dr Myers reviewed some recent publications that showed that rapid tests are being used to test prospective sexual partners and acquaintances and that no sex occurred with partners who tested positive. The numbers in these studies were fairly small however.

Concerns noted by Dr Myers

1. Propensity for self-harm and violence

Similarly although there are no data to support ongoing concerns that HIV home self-testing kits will lead to an increased risk for self-harm and suicide and inter-partner violence Dr Myers noted that more work and study needs to be undertaken in this area.

2. Lost opportunities

In addition Dr Myers noted that home self-testing kits mean there is an increased chance for patients to lose the opportunity to have additional STI testing and to be referred for other appropriate services.

3. False reassurance

A major concern is that some people will be falsely reassured that they are HIV negative when they have false-negative results.

4.Cost

Cost is a real concern because the kit costs US$40 and those most at risk of HIV are those who are most financially disadvantaged. Only 17-18% of people in the US and Europe would be willing to pay this amount for a kit in studies cited by Dr Myers.

5. Risk compensation

There are not yet any data on whether home HIV self-testing kits are associated with risk compensation- meaning an increase in risk-taking.

Dr Myers noted an important study presented at CROI 2013 Abstract#1064 by Katz et al where modeling done around MSM in Seattle suggested that switching from clinic to home-based testing using Orasure would lead to an increase in HIV transmission.

6. Linkage to care

There are not data to show whether use of these tests will lead those people who test HIV positive to seek appropriate medical care. Although 88% of people in the self-test clinical trial presented to the FDA last year said that they would ‘definitely get follow-up’ this remains an important area to monitor and study.

7. Resource constrained settings

Limits of supply chain and also quality assurance.

 During question time Dr Myers got hammered by two audience members who were particularly concerned about how little data there are available about whether home-testing would improve linkage to care in the USA. However, as another audience member noted, the US linkage to care using clinic based testing is pretty poor! This is also an issue that Australia must address.

Point of care assays for immunological and virological monitoring of HIV disease. Abstract 163.

Dr Ilesh Jani, Mozambique

Dr Jani gave a fantastic talk and overview about point of care testing for HIV diagnosis and monitoring regarding POCT for CD4 cell counts and HIV viral load including for children.

Amongst other things he discussed implementation issues and noted:

1. POCT is not error proof. It IS error prone in all phases of testing

2. Implementation of point of care tests is not always done efficiently.

In Mozambique his team's data showed that despite having POCT CD4 instrument on site, they lost 24% of people BEFORE people got tested with the POCT CD4 test. They only managed to test 50% of people on the same day as their HIV diagnosis. Median time to get a CD4 count was 3 days (Jani et al 2011

One key point that I took home from him was that whole blood viral load testing is likely to become common in the future. In patients whose plasma HIV viral is undetectable they may still have a detectable HIV viral load in their whole blood test. He explained that we don’t really know what this means clinically and we don’t know the correlation between plasma and whole blood HIV viral load testing

Accurate cross-sectional incidence testing. Abstract 164

Dr Laeyendecker, NIAID and Johns Hopkins

Dr Laeyendecker gave a masterful talk on this subject, which was valuable for a naïf such as myself. It’s a must watch talk for those who wish to understand how to optimize testing algorithms to assess HIV incidence in populations

Key points include (1) that there is a difference between how HIV clade D versus clades A and C perform in these testing algorithms wherein the tests overcall the prevalence of clade D infections and (2) that multi-assay algorithms perform best for HIV incidence testing in stable, expanding and waning HIV epidemics.

Viral load measures: patients, populations and interpretations. Abstract 165

Dr Irene Hall, CDC

This talk was good. The main point I learnt was that community viral load refers to the viral load of those people who have been diagnosed with HIV. Population viral load refers to all people in a population who are HIV infected including those who are unaware of their diagnosis. This is an important distinction because community viral load does not accurately reflect HIV transmission potential in the community.

Dr Hall noted an excellent oral presentation given at CROI 2013 Abstract 96 which reported on the first study in Swaziland of their HIV population viral load. This household-based counseling and testing study evaluated 18,169 individuals. 5802 individuals were identified as being HIV+ and, of these, only 67% knew that they were HIV+ and, of these, only 50% reported current ART use. A high viral load, defined as >50,000 copies/ml was found in 35% of the total population, (cue heartsink feeling here).

Overall an excellent session.