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Testing disparity between US/EU; duo test availability
Dear Drs. Hook & Handsfield -
First off, thanks for your participation here. It's really fantastic to have access to your expertise. Forum users take note: Hook & Handsfield are world renowned; just check the primary literature, conference proceedings, etc.
I've posted a similar question in the free forum but wanted to lean on your experience. Well worth the $22 but would have rather bought you a coffee and a danish.
There seems to be a disconnect between the US and the rest of the world regarding standard testing protocol. Specifically, the duo/combo approach of testing for viral antigen gauged against the rise of antibodies against HIV
has been in use for over five years in the UK. On a diagnostic level simultaneously testing these two markers that have antagonistic appearance curves makes great sense and demonstrably shortens the testing window period. On an epidemiological level it makes even more sense: facilitate earlier detection, decrease transmission rates, decrease overall incidence and prevalence.
Combo tests have been approved in the US going on nearly two years now (not sure on precise dates, but it's close to that.) I often see recommendations for their use from both of you. However, most clinics don't offer combo tests, most physicians aren't aware of them, and even the big laboratory networks don't seem to offer them. It's surely not simply an issue of cost, since the testing market is obviously a tremendous cash cow and one not necessarily based on medical best practices.
So why isn't the combo test -- with a proven track record of earlier detection and FDA approval -- more widely available in the US?
And on a related question: recently a panel recommended approval of OraSure's home HIV test. I'm curious what your thoughts are on this -- as well as if you think the FDA will actually approve it. Personally, I think it would be a godsend for routine screening.
First off, thanks for your participation here. It's really fantastic to have access to your expertise. Forum users take note: Hook & Handsfield are world renowned; just check the primary literature, conference proceedings, etc.
I've posted a similar question in the free forum but wanted to lean on your experience. Well worth the $22 but would have rather bought you a coffee and a danish.
There seems to be a disconnect between the US and the rest of the world regarding standard testing protocol. Specifically, the duo/combo approach of testing for viral antigen gauged against the rise of antibodies against HIV
has been in use for over five years in the UK. On a diagnostic level simultaneously testing these two markers that have antagonistic appearance curves makes great sense and demonstrably shortens the testing window period. On an epidemiological level it makes even more sense: facilitate earlier detection, decrease transmission rates, decrease overall incidence and prevalence.
Combo tests have been approved in the US going on nearly two years now (not sure on precise dates, but it's close to that.) I often see recommendations for their use from both of you. However, most clinics don't offer combo tests, most physicians aren't aware of them, and even the big laboratory networks don't seem to offer them. It's surely not simply an issue of cost, since the testing market is obviously a tremendous cash cow and one not necessarily based on medical best practices.
So why isn't the combo test -- with a proven track record of earlier detection and FDA approval -- more widely available in the US?
And on a related question: recently a panel recommended approval of OraSure's home HIV test. I'm curious what your thoughts are on this -- as well as if you think the FDA will actually approve it. Personally, I think it would be a godsend for routine screening.
Fantastic response. I really appreciate you sharing your expertise and insight.
MEDICAL PROFESSIONAL
Welcome to the forum. Thanks for your question.
You raise interesting issues. Although I am unaware of any formal data, there does seem to be a lot less reliance on and less use of the duo/combo tests in the US than in Europe and many other parts of the world. I can only guess the reasons, but two come to mind, which were addressed in part a couple of months ago: http://www.medhelp.org/posts/show/1704700:
First, this country has a historic overemphasis on medicolegal liability, leading to excessive caution by health agencies, test manufacturers, etc, which in turn drives formal advice about test reliability at 3 months. Second, the duo tests are formally approved by the US Food and Drug Administration as definitive after 3 months. This in turn is because to claim an earlier window period would require studying large numbers of patients exposed, say, 4 weeks earlier -- and this hasn't been done. As long as there is no regulatory difference between the standalone antibody tests and the duo tests and the former are substantially cheaper, there probably is little incentive for providers, health agencies, and laboratories to switch tests. (I stress that those are only best guesses off the top of my head.)
I have been an advocate of home self testing (HST) for HIV for several years and am glad that a) OraSure's studies have shown that untrained nonprofessionals can do the test accurately and b) the FDA committee has recommended approval. FDA usually goes along with advisory committee recommendations, so I expect the test to be approvved and marketed.
That said, HST may not have a big impact on HIV prevention in the US. Somewhere around 80-90% of people at high risk have been tested, and those who have not may be inherently resistant and won't necessarily use HST. Undoubtedly there will be some benefit in increasing the proportion of HIV infected people who are aware, but the major use of HST likely will be among people at low risk, not unlike those who ask most questions on this forum. (With one possible exception, in the 8 years of this forum no user actually caught HIV from an exposure they were worried about.) And while many such persons will have an easier path to reassurance, some will spend more than they can afford on repeated, unnecessary testing. However, even this may bring some benefit in reducing the number of worried-well visits to STD clinics and other HIV testing facilities.
I hope I'm wrong in these judgments, and also hope health agencies will quickly study test uptake and frequency of newly diagnosed HIV cases. It would be great if there is indeed a signficant rise in newly diagnosed HIV cases.
Thanks again for your interesting question. Best regards--
HHH, MD
You raise interesting issues. Although I am unaware of any formal data, there does seem to be a lot less reliance on and less use of the duo/combo tests in the US than in Europe and many other parts of the world. I can only guess the reasons, but two come to mind, which were addressed in part a couple of months ago: http://www.medhelp.org/posts/show/1704700:
First, this country has a historic overemphasis on medicolegal liability, leading to excessive caution by health agencies, test manufacturers, etc, which in turn drives formal advice about test reliability at 3 months. Second, the duo tests are formally approved by the US Food and Drug Administration as definitive after 3 months. This in turn is because to claim an earlier window period would require studying large numbers of patients exposed, say, 4 weeks earlier -- and this hasn't been done. As long as there is no regulatory difference between the standalone antibody tests and the duo tests and the former are substantially cheaper, there probably is little incentive for providers, health agencies, and laboratories to switch tests. (I stress that those are only best guesses off the top of my head.)
I have been an advocate of home self testing (HST) for HIV for several years and am glad that a) OraSure's studies have shown that untrained nonprofessionals can do the test accurately and b) the FDA committee has recommended approval. FDA usually goes along with advisory committee recommendations, so I expect the test to be approvved and marketed.
That said, HST may not have a big impact on HIV prevention in the US. Somewhere around 80-90% of people at high risk have been tested, and those who have not may be inherently resistant and won't necessarily use HST. Undoubtedly there will be some benefit in increasing the proportion of HIV infected people who are aware, but the major use of HST likely will be among people at low risk, not unlike those who ask most questions on this forum. (With one possible exception, in the 8 years of this forum no user actually caught HIV from an exposure they were worried about.) And while many such persons will have an easier path to reassurance, some will spend more than they can afford on repeated, unnecessary testing. However, even this may bring some benefit in reducing the number of worried-well visits to STD clinics and other HIV testing facilities.
I hope I'm wrong in these judgments, and also hope health agencies will quickly study test uptake and frequency of newly diagnosed HIV cases. It would be great if there is indeed a signficant rise in newly diagnosed HIV cases.
Thanks again for your interesting question. Best regards--
HHH, MD
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