Tuesday, March 9, 2010

Circumcision may increase HIV spread among gay men

We need data, not headline.

It's unconscionable that since early today, this story has been all the public knows about the referenced study.

Here is what little we are told:

"The findings are based on data from 4,889 men who took part in an HIV vaccine trial begun in 1998; 86 percent had been circumcised. During the three-year study, 7 percent of the men became HIV-positive.

When the researchers accounted for other factors -- including demographics, and HIV risk factors like drug use and having unprotected sex -- circumcision showed no effect on the odds of HIV transmission.

Still, Gust and her colleagues point to some limitations of their study, including the relatively small number of uncircumcised men overall and the small number of uncircumcised men who became HIV-positive during the study -- 43"

So, what can the public think with so little to go on?

4,889 men
86% circumcised
7% HIV infection rate
43 intact men became HIV infected

So that means:

4205 circumcised men (4,889 * .86) = 4,205
684 intact men (4,889 - 4,205) = 684
342 men infected (4,889 * .07) = 342
43 intact men infected
299 circumcised men infected (342 - 43) = 299
7.11% circumcised men infection rate (299 / 4205) = .0711
6.29% intact men infection rate (43 / 684) = .0629

Well, isn't that curious. If you stop and puzzle it out, assuming what little data we're given is at least accurate, you find circumcised men had a 13% increase in HIV infection.

13% increased infection rate of circumcised group (.0711 - .0629) / .0629 = .1304

But it's time-consuming and inconvenient to see this fact. In other words, it was spun to favor the hypothesis of the researchers. The same hypothesis which this data resoundingly fails to confirm.

Since the reporters chose a headline expressed as "circumcision (or not) may (or may not) cut (or not cut, or increase) HIV spread among gay men," it would be more in agreement with the study if the headline were "Circumcision may increase HIV spread among gay men."

If that sounds like an overly strong and misleading title, consider that the actual title ("Circumcision may not cut HIV among gay men") must then be more overly strong and misleading, since it is less true to the data.

The first paragraph of the article establishes relative risk reduction as the standard for this sort of study:

"A number of studies in African nations have found that circumcised heterosexual men were up to 60 percent less likely than uncircumcised men to contract HIV during the study periods."

Given the researcher bias in favor of the hypothesis, and the use of relative risk reduction figures for past studies, does anyone think this wouldn't have been expressed as a 13% reduction in HIV, though statistically insignificant, if it had been in favor of the circumcised group?

We are being spun by the researchers (*) while the data is withheld from the public.

(*) The reporters are not making things better.


  1. It has seemed to me for some time that there is a high circ rate and a high AIDS rate in the U.S., and both rates are much lower all over Europe, where the standard of living is about the same, it would seem that circumcision promotes the spread of HIV rather than decreasing it. Could it be that the rougher circumcised penises, known to inflict injury on some women, cause abrasions that allow the virus to pass more easily between partners, and that the foreskin protects the penis of the active partner?

  2. The fact that both the circumcision rate and the HIV infection rate are much lower in western Europe than in the U.S. both areas having a high standard of living, seem to indicate that circumcision promotes the spread af AIDS. This is so obvious that it's hard to understand why it hasn't been publicized more.