“Most patients (68 to 89%) from low risk groups who show reactivity on
screening tests will have false-positive results…The predictive value of a
positive ELISA varies from 2% to 99%…” (Mayo Clinic Proceedings , 1988;
63)
“[I]n low prevalence populations the predictive value [of an HIV test] was
11.1%, while in populations with known HIV-1 infection, the predictive
value was 97.1%. ” (Abbott Laboratories. HIV Antibody Test. April, 1996).
In a high risk group, “The Positive Predictive Value of a home screening
test would be 67%; 33 of 100 would be false positives. With a lower
prevalence the PPV drops to 17%, and 83 out of 100 positive tests would be
false. (“Advances in HIV Testing Technology”- AIDS Education and
Prevention – 1997)
The test manufacturers list the following as their high risk group:
“Prison inmates, STD clinic patients, inner city hospital emergency room
patients… homosexual men [and] intravenous drug users.” (Vironostika HIV
Antibody Test. 2003). And these are the groups that they target for
testing. For these people, HIV tests are nearly 100% accurate. For
everybody else, just 2%.
But all of these numbers are a little confusing. Here’s how it looks in
practice – from the March, 1998 “AIDS Alert” article on rapid tests:
“Whether the tests will perform as well in the United States as they have
abroad is still unknown, experts add. For one thing, using a single rapid
test in a low-prevalence population will give a lower positive predictive
value….That error rate won’t matter much in areas with a high prevalence
of HIV because in all probability the people testing false-positive will
have the disease. But if the same test was performed on 1,000 white,
affluent suburban housewives – a low-prevalence population – in all
likelihood all positive results will be false, and positive predictive
values plummet to zero.” (Coming to your clinic: Candidates for Rapid
Tests. Aids Alert, March 1998)
So, if you take a test, and are “white, affluent and suburban,” you’ll
have a false positive. If you aren’t, even your false positive is a true
positive. Gosh, science is wonderful.
One thing’s for sure – if you are in a high risk group, you can never
really be negative: “If you have a negative test result but you are in a
high-risk group, you may need to have another test 3 to 6 months later.
(“HIV Antibody Tests” McKesson Health Solutions LLC.)
“Testing should be repeated after 6 months in seronegative people whose
behaviour put them at risk.” (Screening for HIV Antibody, Health Canada,
1994)
In the UK, they don’t even wait that long. (From the 2003 UK National
Guidelines for HIV testing) If you test negative but are considered to be
at risk, then “clearly, waiting for six months to test is untenable, ….We
would suggest testing using a sensitive [highly reactive] fourth (or
third) generation screening test immediately after the exposure [the risky
sexual encounter] and then: at one to two months, at three to four months,
and six months.”
They’re thoughtful to add: “Some time and care will be needed to explain
the reasons underlying the need for follow-up testing…despite negative
results.” (“Towards error-free HIV diagnosis: guidelines on laboratory
practice” Communicable Disease and Public Health 2003; 6,4)
But when a low-risk person has a reactive test, the process is quite
different.
If a test is reactive “where the strong expectation is of a negative
result,” – a low-risk population – the patient is not informed that he or
she is HIV positive, or even “very likely infected.” Instead, the process
stops – “Reactivity on these specimens needs very careful scrutiny,
unhurried by inappropriate ‘turn-around’ targets.”
No rush to a verdict for the low-risk patient. What happens next? The
positive result is expunged from the record – through official channels –
and the “expected result” is sought: “Further testing is essential,
employing several different tests carefully selected to minimize the
possibility of each additional test being prone to the same false-positive
effect as gave rise to the false reaction in the initial screening test.”
(ibid)
How do they minimize false positives? They use less sensitive tests, or
interpret them differently. The clinician’s opinion of what the test
should be is considerably more important than test result itself:
“Checking that the final result is not at odds with patients’ clinical and
behavioural characteristics is a key element.” (ibid)
PaulKing - 18 Mar 2005 11:43 GMT
AS OF 1999, IT WOULD SEEM THE ROCHE AMIPLICOR HIV-1
MONITOR TEST IS THE MOST POPULAR PCR "VIRAL LOAD" TEST.
"The Roche Amplicor HIV-1 Monitor(TM) test kit, approved by the FDA, was
used by more than 70% of the laboratories reporting results."
http://www.phppo.cdc.gov/MPEP/pdf/rna/9902rnaa.pdf
The test kit list: http://www.fda.gov/cber/products/testkits.htm
AMPLICOR HIV-1 MONITOR(TM) TEST
"The AMPLICOR HIV-1 MONITOR Test is not intended to be used as a screening
test for HIV or as a diagnostic test to confirm
the presence of HIV infection."
http://www.fda.gov/cber/pma/p9500054.htm
http://www.fda.gov/cber/PMAlabel/P9500054LB.pdf
NucliSens(R) HIV-1 QT -- HIV QT Nov. 13, 2001
"The NucliSens(R) HIV-1 QT assay is not intended to be used as a screening
test for HIV-1 nor is it to be used as a diagnostic test to confirm the
presence of HIV-1 infection."
http://www.fda.gov/cber/pma/p0100010.htm
http://www.fda.gov/cber/pmalabel/P0100010LB.pdf
COBAS AmpliScreen HIV-1 Test, version 1.5
Approval Date: 12/19/2003
"This test is not intended for use as an aid in diagnosis."
http://www.fda.gov/cber/products/hiv1roc121903.htm
http://www.fda.gov/cber/label/hiv1roc121903LB.pdf
Procleix(R) HIV-1/HCV Assay -- IN0076-01, Rev. A
Approval Date: 6/4/2004
"The Procleix HIV-1 Discriminatory Assay may be used as an aid in the
diagnosis of HIV-1 infection."
http://www.fda.gov/cber/products/hivhcvgen060404.htm
http://www.fda.gov/cber/label/hivhcvgen060404LB.pdf
GENETIC SYSTEMS (TM) rLAV EIA
"The rLAV EIA is intended to be used as a screening test for donated blood
or plasma and as an aid in the diagnosis of infection with HIV-1."
http://www.fda.gov/cber/products/hiv1gen062998.htm
http://www.fda.gov/cber/sba/hiv1gen062998S.pdf
VIRONOSTIKAT(R) HIV-1 PLUS O MICROELISA SYSTEM
"System is intended for use as an aid in diagnosis of infection with
HIV-1. It is not intended for use in screening blood donors."
http://www.fda.gov/cber/pma/P020066.htm
http://www.fda.gov/cber/pmalabel/P020066LB.pdf
THE CAMBRIDGE BIOTECH HIV-1 WESTERN BLOT KIT
"Accurate diagnosis of HIV-1 infection is important in determining an
individual's risk for developing AIDS. Accuracy is complicated by
false-positive and false-negative (EIA) results. It would appear that in
some limited infections, a compartmentalized response occurs in which
expression of HIV-1 or its respective Immune response is limited to a
restricted number of organs and tissues.(17)"
"Slight ambiguities exist in the designation of the molecular weights of
the HIV-I antigens. The designations listed in Figure 1 have been
established by both internal testing with known markers and consensus of
published
literature.(5-10)"
"Although a blot POSITIVE for antibodies to HIV-1 indicates infection with
the virus..."
"POSITIVE blot results using any specimen type (serum, plasma, or urine)
should be followed with additional testing. Such testing may rely on
alternative test methods or specimen types. The clinical implications of
antibodies to HIV-1 in an asymptomatic person are not known."
"The sensitivity ... using urine was evaluated by comparing the urine
results to the results obtained from testing paired serum specimens
collected from individuals who were HIV-1 seropositive and from
individuals clinically diagnosed as AIDS patients."
http://www.fda.gov/cber/products/hiv1cam052898.htm
http://www.fda.gov/cber/label/hiv1cam052898Lb.pdf
OraSure(R) HIV-1 Western Blot Kit
"The OraSure HIV-l Western Blot Kit is an in vitro qualitative assay for
the detection of antibodies to individual proteins of the Human
Immunodeficiency Virus Type 1 (HIV-l) in human oral fluid specimens
obtained with the OraSure HIV-l Oral Specimen Collection Device.
The OraSure HIV-l Western Blot Kit is not intended for use with blood,
serum/plasma or urine specimens, or for screening or reinstating potential
blood donors."
http://www.fda.gov/cber/pma/P950004.htm
http://www.fda.gov/cber/pmalabel/P950004Lb.pdf
Reveal(TM) Rapid HIV -1 Antibody Test
"The Reveal" Rapid HIV -1 Antibody Test is intended for use as a
point-of-care test to aid in the diagnosis of infection with HIV -1. This
test is suitable for use in multi-test algorithms designed for statistical
validation of rapid HIV test results."
http://www.fda.gov/cber/pma/p000023.htm
http://www.fda.gov/cber/pmalabel/P000023LB.pdf
PaulKing - 18 Mar 2005 11:47 GMT
Hidden Facts and Dangers of HIV Tests
What's in the Fine Print
Remarkable information about HIV tests including the fact that no HIV test
has ever been approved by the US Food and Drug Administration for the
actual diagnosing of HIV infection.
Few doctors, clinics, journalists, or AIDS organizations know that all
current HIV tests are approved only as screening tests, prognostic tests
(for predicting a possible future outcome) or as "an aid in diagnosis" and
are not intended to be used for determining if a person actually has HIV.
The FDA's lack of such approval speaks to the fact that no HIV test can
directly detect or quantify HIV or determine the presence of specific HIV
antibodies in human blood.
Recent changes in the fine print of the test kits acknowledge this little
known data and seem to indicate a change of thought with regard to the
role of HIV in AIDS.
From 1984 until last year, test literature contained the very certain
statement that "AIDS is CAUSED by HIV." Then in November of 2002, a new
test kit started what now seems to be a trend toward rethinking the causal
link between HIV and AIDS. It states, "AIDS, AIDS related complex and
pre-AIDS are THOUGHT TO BE CAUSED by HIV." (OraQuick Rapid HIV-1 Antibody
Test, OraSure Technologies, Inc)
Now it appears we've gone from "HIV is thought to cause AIDS," to
something even more uncertain: "Published data indicate A STRONG
CORRELATION between the acquired immunodeficiency syndrome (AIDS) and a
retrovirus REFERRED TO as Human Immunodeficiency Virus (HIV)."
This last quote is found in the package insert for a new ELISA test
(Vironostika HIV-1 Plus O Microelisa System) the FDA approved in June
2003.
The entire package insert can be downloaded from
http://www.fda.gov/cber/pma/P020066.htm
According to Alive & Well advisor Dr Rodney Richards, a chemist and
co-creator of the very first HIV test, as of June 2003, the number of FDA
approved tests that contain the term HIV or LAV (the old school term for
the so-called virus) have risen to 36. Of these, 13 have been approved in
just the last three years.
Richards points out that "despite the increased number of HIV tests, there
is still no manufacturer that claims their test can be used to diagnose
infection with HIV. All of the RNA based tests for viral load and
genotyping clearly state they are 'NOT intended for use in diagnosing HIV
infection.'
Instead of an indication for use in detecting or quantifying the actual
virus, these tests are approved only for prognosis or monitoring therapy
for people who doctors assume are infected.?
Richards is working on a document to clarify what HIV test manufacturers
mean by the terms "prognosis," "monitoring of therapy," and "aid in the
diagnosis of HIV." His report will focus on what the tests cannot do
(diagnose HIV infection) and what exactly they can.
At first glance, the rapid tests may appear relatively benign since the
manufacturers clearly emphasize that "preliminary positives" must be
confirmed with follow up testing.
This emphasis is due to the fact that the accuracy of the rapid tests? is
widely known to be more questionable than the already dubious HIV ELISA or
Western Blot. But the notion that medical personnel will await
confirmation of results before insisting patients take action is entirely
misguided since the true market for rapid tests is pregnant women in
labor
Incredibly, the recommendation to misuse rapid tests for women in labor
comes directly from the Deputy Commissioner of the FDA himself, Dr. Lester
M Crawford.
The good doctor says "OraQuick will be a great help in identifying
pregnant HIV-infected women going into labor who were not tested during
pregnancy so that precautionary steps can be taken to block their newborns
from being infected with HIV." (FDA News, November 7, 2002)
These precautionary steps include IV infusion of the toxic chemotherapy
AZT during labor, C-section delivery, six weeks of mandatory AZT treatment
for the baby regardless of their own HIV status, and orders to the mother
not to breastfeed.
Even though chemotherapy, surgery and denial of normal feeding are based
on preliminary results from a test never approved for detecting HIV
infection, a mother who declines such intervention risks losing custody of
her child.
Perhaps more remarkable than official calls for misuse of rapid tests is a
disclosure by the manufacturer of the OraQuick that 7% of women with a
history of prior pregnancy will score falsely positive on their test.
Further, the manufacturer of the newly approved Reveal test didn't even
evaluate their product in multiparous women.
Worse still, as Dr Richards points out, the rapid tests may soon be
routinely administered to women tested negative before labor. "Based on
the erroneous belief these tests can actually diagnose HIV infection,
doctors may want to retest women in labor who?ve previously come up
negative just to be sure they haven't seroconverted in the mean time."
Another lucrative market for the rapid tests is among healthcare workers
who experience accidental needle sticks or other unintentional contact
with patient fluids. As Richard points out, this opens a Pandora?s box of
potential life-altering situations.
"Imagine a nurse sticks herself with a used needle. Ora-Sure gives her the
impression she can find out quickly if that needle is contaminated with
HIV. Should the needle score positive, she would then be urged to start
prophylactic chemotherapy right away.
Of course, if the needle scores positive, hospitals would most likely feel
an ethical responsibility to
inform the patient and to urge them to also start 'saving their lives'
with AIDS meds.
Since there are 600,000 to 1,000,000 accidental needles sticks in the US
annually, this is a huge market for both the test and treatment
manufacturers."
The great influence of drug and test manufacturers on public health
policy, media presentations and among AIDS activist groups may mean that
the hidden dangers of rapid tests will remain unknown.
PaulKing - 21 Mar 2005 03:40 GMT
Seems Carter and friends have no answer to this one.
Nice change from their usual BS.