Question on accuracy
Having looked at some studies on older rapid tests available around the world and how their accuracy deviates quite a bit from the manufacturers guarantees, how can we trust the reliability of biosure? Have there been any studies in biosure particularly relating to acute infections? Was this something tested when acquiring the regulatory approval? Are there any plans to roll out third and fourth gen testing and why was 2 no gen testing applied when there are other rapid tests available testing for Img?
Gary Carpenter, BioSure (UK) Limited
Work on 01st December 2016
The reason that the test can detect 5 days after a laboratory antibody test is that once the process of antibody production starts output is very high. So the 5 day lag seems reasonable. So if the person infected didn't create antibodies until 60 days the BioSure HIV Self Test would probably detect on the 65th day.
As far as I am aware there are 4 tests with some sort of regulatory approval for HIV self testing: all of them are 2nd generation tests. We actually supply NHS clinics in the UK with a 3rd generation point of care rapid test, but even in NHS clinic settings they all apply the 3 month window period, regardless of the type of test used. HIV clinicians use the British HIV Association guidelines for rapid point of care testing, why would we go against that? We need to encourage more people to know their HIV status, so all stakeholders involved in HIV testing need to have the same voice.
Again I hope that this helps.
Used on 30th November 2016
By the way 5 days average detection rate after laboratory tests sounds unbelievable and reassuring and a credit to the makers.
Used on 30th November 2016
Thank you for the great reply, cleared up a lot of the questions, sorry I was wrongly under the impression that there were self test kits in other countries using third generation as I presume rapid tests in clinics use these. I guess these questions arise from testing in the later stages of the window period i.e. After 2 months where a lot of the experts say regardless of the test everyone should test positive for antibodies. Obviously it is easier for certain people to take a more liberal stance on that and their clinical experience may be different to what you have witnessed with your testing of the device. Regards barry
Gary Carpenter, BioSure (UK) Limited
Work on 30th November 2016
Hi Bary d
Thanks for your question. This is going to be a very long answer, so please bear with me!
You are quite right, rarely does a test match up to manufacturers product insert claims for accuracy, which is why we have chosen to select evidence based accuracy figures, so nit entirely based on performance evaluations that we have been directly involved in.
In order to get a CE mark there are extremely strict guidelines that set out exact what studies need to be performed and how accurate the test needs to be. These are non-negotiable. When the BioSURE HIV Self Test received it's CE mark, it was the first product to get through. HIV tests are considered by regulators to be very high risk. Combining these two facts meant that the evidence provided about product accuracy and safety was put under incredible scrutiny. We chose to apply to BSI (the British Standards Institute) for CE Mark. BSI are one of, it not the most highly regarded regulatory organisations in the world. Our self test study was conducted by the The Centre for Sexual Health and HIV Research, University College London, one of the world's premier research universities. So we set the bar very high.
The test device itself has been received approval by the World Health Organisation's Prequalification Team for IVD's.
Part of all regulatory approval processes is testing with "seroconversion panels". This determines the ability of the test to detect acute infections. The test was shown to detect HIV infection on average 5 days after highly sensitive laboratory tests for HIV detected the infection.
We do not believe that at present that the technology is right for 4th generation rapid point of care tests (like to BioSURE HIV Self Test). The antigen line has been shown to be extremely inaccurate. The manufacturers of these tests might get it right one day and then we might look again. Laboratory 4th generation ELISA tests (detecting both antibodies to HIV and p24 antigens) are extremely sensitive to early HIV infection.
At the moment whether we had a 2nd or 3rd generation strip at the heart of the BioSURE HIV Self Test, we would still stick to the same advice. All HIV blood sample based antibody rapid tests are extremely sensitive and specific, regardless of their generation. (Generation is not dependent on how new the device is but is based on the antibody capture mechanism deployed. All currently approved HIV self tests are 2nd generation, by the way). But even if we did have a 3rd generation strip in the test, we would still only make a claim for a 3 month window period. The biggest single factor in the earliest time of detection of antibodies comes from the individual person, not from the test. Theoretically it is possible that the BioSURE HIV Self test COULD detect from 24 days after infection. But only if the person had started the process of antibody creation. This varies hugely, from 20 days to 3 months. A false negative result (i.e. a negative test result when the person is actually HIV positive) is the biggest safety risk. So why take a risk with other people's health. So our testing window period will always be based on this guidance. Which by the way is the based on BHIVA guidance and is the same advice you would get from NHS GUM Clinics that offer HIV rapid point of care testing, again regardless of the generation of test used.
For any self test the accuracy of the result is completely dependent on the ability of an untrained user to correctly collect the required amount of sample, apply the sample and any other facilitating solutions to the test. So whilst the biochemistry is really important, that by itself means nothing if the test device isn't easy and intuitive to use. We know a lot about HIV tests and we know that there is no test easier to perform than the BioSURE HIV Self Test.
I hope that I've answered your questions and hope you've made it this far through my answer. Sorry it was so long!!
BioSure (UK) Limited