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At $200 - $300 per Test, When Are HIV Viral Load Assays a Bargain
and Perhaps a Lifesaver?
By
Paul Galatowitsch, Antonio Urbina and Timothy Law Snyder
 Paul
Galatowitsch is a health care consultant. Antonio Urbina is the
director of clinical HIV and AIDS education at St. Vincent's Hospital.
Timothy Law Snyder is a professor of mathematics and computer science
at Fairfield University.
In
the summer of 2003, a young man went to his doctor complaining of
a high fever, headache, painful joints and muscles and a rash. His
doctor diagnosed the flu, and told him to rest and drink plenty
of fluids. After a week, the man's symptoms went away.
Unknown
to this young patient and his doctor, however, those symptoms were
caused by a very recent infection of HIV, the virus that causes
AIDS.
An HIV testing technology that has been around for more than a decade can diagnose
recent infections like this man's. Unfortunately, the technology
is rarely used in New York City.
In
this patient's case, his partner had infected him two weeks earlier,
and his body was responding to the unchecked replication of HIV.
Although 10 to 40 percent will not experience these flu-like symptons,
every person who becomes infected with HIV goes through acute
HIV infection.
This phase of infection presents an enormous risk both to the person
who has become infected and to his sexual partners.
Here's
why: during the peak stage of early HIV infection, the amount of
the virus circulating in the newly infected person can make him
up to 1,000 times more likely to transmit HIV than during the chronic
stage of the infection, which is typically eight years or more after
infection and before the onset of AIDS. Had the young man's condition
been properly diagnosed, he could have been told that any sexual
activity during this initial phase of infection would be alarmingly
dangerous to others.
Surprisingly,
such misdiagnosis is routine. Despite the availability of a reliable
method to detect this initial phase of infection, the polymerase
chain reaction viral load test, medical providers worldwide will
diagnose only about one of every 60,000 cases of acute HIV infection.
And this is a considerable problem in reducing the spread of HIV
The
viral load test detects HIV itself, unlike the more
standard HIV test, which detects only the antibodies that develop
weeks or more rarely months after infection. Indeed, most people
will get negative results on an antibody test for three to six weeks after infection.
The
viral load test, however, can detect HIV five to seven days after
infection, and since the first few weeks correspond to the period of
highest infectivity, detection then is the most useful in stopping
the spread of the disease. Unfortunately, commercial viral load
tests are expensive, at $200 to $300 each. As a result, health care
providers avoid using them, and instead rely on the antibody test,
which costs about $5 [Physicians periodically do order HIV RNA
testing for their HIV patients, but only for those who are chronically
infected, to monitor their viral loads as a means of evaluating
the effectiveness of therapy or to help determine the appropriate
time to initiate or change treatment--Ed]
But
North Carolina has discovered a way to get around the high cost.
Since 2002, the state has submitted the blood of every person testing
negative for antibodies at its sexually transmitted infection clinics
to viral load testing through a blood pooling system. In a May 2005
issue of the New England Journal of Medicine, Christopher
Pilcher and his colleagues, who run the North Carolina viral load
testing program, explain that all HIV negative blood samples are
pooled into batches of 90 and tested. If a batch tests positive,
it is examined sample by sample until the positive specimens are
found.
By
pooling tests, North Carolina has reduced the cost of a combined
HIV antibody and viral load test to $3.63, from $90, the noncommercial
state's cost. In 2004, North Carolina's pooled testing program identified
an additional 6 percent of HIV cases at its clinics. San Francisco
established the same testing program in 2003, and has identified
10 percent more HIV infections.
By
our conservative calculations, if New York City submitted the approximately
38,000 HIV tests it conducts annually to a combined viral load and
HIV antibody testing program; it would identify 24 to 36 cases of
acute HIV infection and avert 6 to 72 HIV transmissions each year.
Multiplying those figures by $300,000, the lifetime cost of treating
a person with HIV, shows that pooled viral load testing would save
the city $1.8 million to $21.6 million each year.
Unfortunately,
New York City's Department of Health has refused to use this procedure
at its sexually transmitted infection clinics. Instead, by January
2005, the department had shifted all of its resources to rapid
HIV antibody testing, a procedure that provides results
in one hour but cannot determine acute HIV infection. The
decision not to combine rapid HIV antibody and viral load testing
will incur needless tragedies for many New Yorkers and cost the
city millions of dollars in additional health care expenses.
07/20/05
Source
P
Galatowitsch, A Urbina and T L Snyder. Breaking the AIDS Chain.
The New York Times (Op Ed). July 17, 2005.
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