HIV home testing is soon likely to become legal in the United States, following a unanimous vote in support of the OraQuick In-Home HIV Test by a panel of experts advising the Food and Drug Administration (FDA).
The test that may be made available over-the-counter is designed to be used at home, without medical supervision. A sample is taken by swabbing an absorbent pad around the outer gums, adjacent to the teeth; the results are given in twenty minutes.
The 17 members of the Blood Products Advisory Committee (BPAC) voted unanimously that the benefits of the test outweigh its potential risks for consumers. While the test is not as accurate as professionally-administered tests, the panel felt it could provide an important way to make HIV testing available to more people.
The FDA is not bound to follow the recommendations of its advisory committees, but usually does so. This would be the first complete home-based screening test for any infectious disease available for purchase from US pharmacies and internet retailers.
The panel heard overwhelmingly supportive public testimony from more than two dozen witnesses including HIV activists, black community representatives and public health experts.
While this would be the first legal home-testing kit in the US, home sampling for HIV antibody testing is already legal there.
When using a home-sampling kit, the individual takes an oral fluid or blood sample in their own home and mails it to a laboratory, which will make the results available online or by phone. With home-testing kits (as with a pregnancy test), the individual takes a sample and interprets their results on their own.
Until now, only home-sampling tests have been legally available in the US and UK.
The OraSure company has adapted its OraQuick Advance test for use by individuals who do not have medical training. Whereas the professional version can test either oral fluid or a fingerprick blood sample, the OraQuick In-Home HIV Test is only for testing oral fluid.
However a recent meta-analysis found that the professional-administered OraQuick test had slightly poorer performance when testing oral fluid samples than when testing blood samples. In particular, the test’s sensitivity was slightly lower than ideal.
The home test kits come with detailed instructions and links to free telephone support. Whereas the professional kits are sold for less than $20, the home version is likely to be more expensive, but no more than $60.
To prepare for possible regulatory approval, the manufacturers conducted a number of studies, culminating in a Phase III trial which enrolled 5499 individuals who did not know their HIV status. Most were from US communities in which HIV infection is relatively common, whereas 1109 were from low-prevalence communities.
Participants had blood taken for a traditional antibody test conducted in a laboratory and then took away the OraQuick In-Home HIV Test for self-testing. They returned on another visit, told the researchers the result the home test had given them and were informed of the laboratory test result, which is the benchmark against which the home test was judged. Individuals who needed them were referred on for counselling and linkage to care.
The key measures of test accuracy are sensitivity (the percentage of results that are correctly positive when HIV is actually present) and specificity (the percentage of results that are correctly negative when HIV is not present).
The study found that sensitivity was 93.0% and specificity was 99.98%.
Of 114 individuals who really did have HIV infection (as determined by the laboratory blood test), 106 individuals were correctly identified by the home test. In other words, eight people were given false negative results, when they should have been told that the result was positive.
This translates to the figure of 93% sensitivity. It is also it important to note the 95% confidence intervals when interpreting these figures (see the table below). Confidence intervals represent plausible estimates within which the ‘true’ figure may lie – for example, sensitivity could be as low as the lower figure given, 86.6%.
Moreover the panel noted the poorer performance of the home test compared to the professionally administered version. The table compares the results of the home-testing trial with that of a recent meta-analysis of the OraQuick test used by professionals.
|
Sensitivity (95% confidence interval) |
Specificity (95% confidence interval) |
|
|
Home testing (oral fluid) |
93.0% (86.6-96.9%) |
99.98% (99.90-100.0%) |
|
Professionally administered (oral fluid) |
98.03% (95.85-99.08%) |
99.74% (99.47-99.88%) |
On the other hand, the specificity results were extremely encouraging. This means that there were extremely few false positive results and that the test was very accurate when used with low-prevalence groups.
Around 1 in 100 users were unable to get a test result, usually because of mistakes in following the instructions or because of uncertainty in reading the results.
Panel discussion reflected not only the accuracy of the test itself, but the potential for a home test to expand HIV testing.
Dr Elliott Cowan of the FDA argued that the test would have a net public health benefit. “The OraQuick In-Home HIV Test is expected to be associated with a net increase in the number of HIV infections newly identified each year,” he said.
A number of witnesses urged the panel to back the test as a means of eliminating HIV's public stigma, a main barrier to testing, by making the home test just another item that can be purchased at a local pharmacy along with aspirin or condoms.
Witnesses were particularly hopeful that home testing could reach women and ethnic minorities who are not being effectively reached by existing testing programmes.
“There has been a lot of talk about the false-negative test results,” said panellist Dr Steven Pipe. “But I still can’t get over the fact that 20 percent of people living with HIV haven’t been tested. If the in-home test helps to reduce this number, its benefits ultimately outweigh its risks.”
Therefore the committee voted unanimously that the trial results provide reasonable assurance that the test is safe and effective for its intended use. They also agreed unanimously that the projected benefits of the test outweigh the potential risks of false positive and false negative test results.
The panellists also noted the need for strong, clear and concise information in the educational materials that will accompany the test to minimise human error, spell out the risks of false-negative test results and, importantly, to link those who do test positive to appropriate healthcare providers for follow-up testing and care.
Whereas home-sampling kits are legal in the UK, home-testing kits are not. Under UK law, HIV testing can only be provided by medical professionals and test equipment cannot be sold to members of the public for home testing. Nonetheless, unregulated products of questionable quality are available through the internet.
Following lobbying by the Terrence Higgins Trust, the National AIDS Trust and a House of Lords select committee, the government has said that it plans to change the law and allow licensed, quality-assured home-testing kits to be made available.
FDA Blood Products Advisory Committee. OraQuick® In-Home HIV Test Sponsor Briefing Document. (Full text freely available).
Pant Pai N et al. Head-to-head comparison of accuracy of a rapid point-of-care HIV test with oral versus whole-blood specimens: a systematic review and meta-analysis. Lancet Infectious Diseases 12: 373-380, 2012. (Full text freely available).
