Debate Flares over Whether Circumcision Curbs
HIV
By Ker Than, LiveScience Staff Writer
A new study slamming the link between male circumcision and reduced
HIV transmission is itself being slammed by HIV scientists who
say the author is not qualified to make such claims and worry
his findings will be accepted as scientific consensus by the public.
Numerous studies by biologists and medical researchers have indicated
circumcision can significantly reduce a male’s risk of contracting
HIV during heterosexual sex.
However, in a study released on June 20 in the online journal
PLoS One, John Talbott says such claims are based on faulty statistical
analyses. Talbott re-analyzed the data used in a widely cited
study published in a 2004 issue of the Journal of Acquired Immune
Deficiency Syndromes (JAIDS) and found that male circumcision
(or lack thereof) is not a good predictor of a country’s
HIV infection rate. Rather, he proposed, the number of infected
prostitutes in a country should be used to estimate that area’s
HIV infection rate.
Talbott is a former vice president of the investment banking
division of Goldman Sachs in New York City and has no formal training
in biology or epidemiology.
Lack of skepticism
Since its publication, Talbott’s study has garnered increasing
coverage from news outlets and bloggers, some of whom have treated
the findings as undisputed fact. This concerns HIV researchers
who say Talbott’s own analysis is misleading and that it
suggests, falsely, that African women are more likely to be prostitutes
than women in other parts of the world.
“Not only is this epidemiologically questionable ... but
it seems like a misleading and potentially harmful assertion to
be making, which could even be perceived by some as playing on
racial stereotypes,” said Daniel Halperin, an HIV specialist
at Harvard University and a co-author on the earlier study that
Talbott disputes.
Other researchers worry Talbott’s claims could leave the
public with a false impression that the link between HIV and circumcision
is still a hotly debated issue. “There’s no doubt
about it. John Talbott’s really out on a limb here,”
said Helen Weiss, an HIV researcher at the London School of Hygiene
& Tropical Medicine. “It’s just not a question
anymore. And it’s quite frustrating that he’s getting
all this publicity, because we’ve moved beyond.”
In his study, Talbott refers to other research that found that
up to 4.3 percent of the women in African capital cities are prostitutes.
These sex workers, many of whom are infected with HIV, are the
primary vectors for transmission of the disease among the population,
Talbott contends.
Talbott’s critics say his study does not explain why countries
such as Angola, Madagascar and the Philippines have relatively
low rates of HIV infection (about 4 percent, 2 percent and less
than 0.1 percent, respectively) despite their having very active
sex-worker communities.
Talbott contends that these outliers do not discredit the trend
his analysis shows. “Whenever you do a regression analysis
for 77 countries, it’s very easy to go in and find the three
data points that don’t support the theory perfectly,”
Talbott said in a telephone interview. “Just because there’s
a correlation across 77 countries, it doesn’t mean it applies
to every country.”
Other explanations for the disconnect between prostitute numbers
and HIV infections, Talbott said, might be that many countries
are underreporting their HIV infection rate, or that countries
with high prostitution rates but low rates of infection do a better
job of keeping track of and testing resident prostitutes.
“For example, in Argentina...they keep them in the bars
and restaurants,” Talbott said. “[The prostitutes]
don’t cruise the street, and [the governments] monitor and
test them regularly.”
A proven method
Ultimately, Halperin said, results from ecological studies—which
rely on the statistical analysis of data from populations or groups
of people rather than individuals—such as the one Talbott
is refuting are not solid enough to base health policy decisions
on.
Ecological studies “are in many ways the lowest rung of
the food chain in epidemiology. Randomized trials are the strongest
level of evidence," Halperin said.
Halperin said the findings of the 2004 JAIDS paper have been
validated by results from other studies, including randomized
trials that involved following the infection rates of circumcised
and uncircumcised African men. Those trials found that circumcision
was up to 60 percent effective in preventing male HIV infection
during heterosexual sex.
"It is the higher-level data, like randomized trials, which
have convinced many international organizations including WHO
and UNAIDS regarding the protective effect of male circumcision
for heterosexual HIV transmission," Halperin said. "They
have concluded, after much internal and external debate, that
an intervention which is at least 60 percent effective should
be made available to those men who seek out the service."
“They were very skeptical at first...but once people actually
sat down to look at the data, you’re not left with a choice
really if you want to do something about HIV prevention,”
Weiss said.
Weiss stresses that scientists are not saying circumcision is
the only way to curb HIV infection. Rather, they are recommending
that it be integrated into other intervention strategies, such
as regular condom use and behavioral changes.
“Everybody wishes there was a vaccine or there was some
easy way of reducing HIV risk,” Weiss said. “Nobody
wants a surgical intervention which has got some risk associated
with it. But the fact is this is the only proven effective intervention
for adult transmission. And we can’t ignore it. I think
it’s unethical to ignore it.”
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