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I've seen numerous claims that circumcision reduces HIV risk, both on TV and online.

Have there been any studies to verify if circumcision does or doesn't reduce HIV risk in a statistically-significant manner?

Oddthinking
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luvieere
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    Rather important: compared to *what*? Uncircumcised but wearing a condom? – Konrad Rudolph Jun 08 '11 at 17:55
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    @Konrad -- The only useful question is without a condom for both :P Clearly once you put a condom on.... – Russell Steen Jun 08 '11 at 17:59
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    @Russell On the one hand, yes. On the other hand, this is a loaded statement (people *do* use the supposed preventative effect of circumcision to argue against wearing condoms, which is playing with fire). See also Darwy’s answer. – Konrad Rudolph Jun 08 '11 at 18:52
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    @Konrad -- My experience is that people will use just about anything they can get their hands on to argue for not using a condom. By that logic we shouldn't pursue any improvements in non-condom prevention, because people might use it to argue against wearing condoms. – Russell Steen Jun 08 '11 at 19:46
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    As you look through the evidence in the answers below, I suggest it might help to keep in your head the following questions: Are the studies looking at a population of men who have sexual encounters with other men, a population of men who only have sexual encounters with women, or a real world sample including a mix of both? Are they looking at the risk of a woman being infected by a man, a man being infected by a woman, a circumcised man being infected by an HIV positive man, or a man being infected by a circumcised HIV-positive man? This may explain some of the apparent discrepancies. – Oddthinking Jun 09 '11 at 11:22
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    @Oddthinking -- I agree. Though to a point (and to the question), if a study shows that it reduces the risk for female to male transmission, then it does reduce the risk overall, from a pure statistical and scientific standpoint. I think people are confusing the raw research with potential policy implementation concerns and that those potential policy/social concerns drive most if not all of the objections. – Russell Steen Jun 09 '11 at 13:22
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    I stumbled over [this recent study](http://sciencespeaksblog.org/2011/07/20/male-circumcision-curbs-spread-of-hiv-over-time-risky-behavior-does-not-increase/), and I would be interested if @Russell, Darwy or others would like to incorporate it into their answers. – Oddthinking Jul 24 '11 at 12:06
  • @Darwy, I wasn't permitted to name-check you in the previous comment. – Oddthinking Jul 24 '11 at 12:07
  • Related: [Are there any health benefits to male circumcision?](http://health.stackexchange.com/q/13/114) at HS – kenorb Apr 24 '15 at 01:51
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    In any case what we can determine from all of this is that the near-automatic circumcision of male children in USA and Canada is irrelevant for "health" reasons. The same health benefits can (if deemed necessary) be obtained by those individuals through other means. –  Feb 20 '16 at 19:43

3 Answers3

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I would have to respectfully disagree with Russell's answer and say: No. Circumcision does not reduce HIV risk.

The three controlled intervention trials suffer from some VERY major design flaws, which cast more than a reasonable doubt about the supposed 'benefit' of circumcision in males.

A Cochrane review of circumcision questions the validity of previously performed studies on circumcision for the following reasons:

  • Performance bias
  • Attrition bias
  • Selection bias

They identified 14 cross sectional studies with inconsistent findings - 4 were statistically significant for a benefit to circumcision, 2 were statistically significant for harm from circumcision. They also mentioned study heterogeneity.

They summarize with (bolded emphasis mine):

In assessing the quality of the observational studies we identified 10 potentially important confounders that studies would need to ensure were either balanced between circumcised and uncircumcised groups or, if unbalanced, that were adequately adjusted for (see Box 2).

Many studies either did not measure these variables or, if reported, were either not balanced between groups or not adjusted for.

It is important to note that observational studies, unlike RCTs, can only adjust for known confounders, and only then if they are measured without error. The effect of unknown confounders may well be operating in either direction within and across all of the included studies.

The studies from high-risk groups included in this review do report a powerful protective effect of circumcision, measured by both unadjusted and adjusted odds ratios. More mixed results were reported for the general population. As all the observed results could be explained by likely confounding, RCTs are essential before circumcision is implemented as a public health intervention. Implementation of circumcision will encounter cost, both financial and in terms of potential personal harm; no adverse effects are reported in this review only because none of the observational studies investigated them. Feasibility issues of implementation are beyond the scope of this review but need to be carefully considered.

If those clinical trials in Africa are flawed, how can one justify using them as the basis for a policy?

There is a real risk of risk compensation reducing the 'benefit' of circumcision.

The various pro-circumcision studies all cite the need for 'other' forms of prevention, ie. condoms - which in Africa aren't as available (or used) as they are elsewhere in the world.

Further Reading:

I'll be happy to counter the other sources at a later point, it's 10:30 pm here and I'm knee deep in setting OEL limits.

Community
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Darwy
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  • it also worth reading one of the editorial notes on (afaik) the first paper that was written on this subject: http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.0020293 It concludes with: "Ultimately, if these results are correct, then this is a study that offers hope. Clearly, further randomized studies will be needed to confirm the results (one in Kenya is scheduled for completion in 2007), but to not put this paper in the public domain quickly could be considered unethical in its own right." – johanvdw Jun 08 '11 at 18:30
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    The CDC page cites over a dozen different studies, both lab and clinical trials. You've questioned one set of clinical trials. One set of trials being flawed does not invalidate an entire body of research. – Russell Steen Jun 08 '11 at 18:36
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    I've questioned all 3 clinical trials, as they are all based upon the same sampling bias, selection bias, etc. How a group of researchers can put forth a recommendation for a procedure such as circumcision as a preventative measure for HIV with no long-term follow up period is unforgivable. – Darwy Jun 08 '11 at 18:39
  • Further issues with the refutation you link: It opens with "The results of three randomized clinical trials (RCTs) are often presented as proof beyond a reasonable doubt that male circumcision prevents HIV infection.2 After all, RCTs are the gold standard of medical experimentation. " -- Straw man, they are presented as evidence that they reduce risk, not completely prevent. – Russell Steen Jun 08 '11 at 18:40
  • Darwy -- There were more than three clinical trials. There lab studies you have not addressed at all. How you can maintain your stance against over 15 years of research simply by questioning a small portion of that research is unforgiveable. – Russell Steen Jun 08 '11 at 18:42
  • Futher issues from the refutation: " A basic assumption adopted by the investigators was that all HIV infections resulted from heterosexual transmission, so no effort was made to determine the source of the infections discovered during the trial." -- Also false, which is covered again in the CDC writeup. Confounding factors were included and researched both in the original studies and in follow-up studies and meta-studies. I think my point has been made here. – Russell Steen Jun 08 '11 at 18:43
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    Russell, all the proof you've linked relies on those 3 clinical trials as the basis for the conclusion that circumcision reduces HIV risk. It's a circular argument. Let's examine the Uganda clinical trial: "Male circumcision for HIV **prevention** in men in Rakai, Uganda: a randomised trial" They're not talking about 'risk reduction' they're talking about PREVENTION. There is no strawman there. – Darwy Jun 08 '11 at 18:48
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    The CDC has sources from up to 2005. My sources are from 2008 and 2011. Despite the circumcision page, the CDC does not come out and recommend circumcision as a procedure for men and infants in the US. – Darwy Jun 08 '11 at 18:53
  • You're arguing strawmen and tangeantal points. For instance, research showing that it does not reduce female risk does not disprove anything about male risk. No one is claiming that it's a solution, only that it reduces risk, so all studies and arguments that it's not perfect are against a strawman argument. Your one quote from one link is taken out of context from the body of the study. There's a LONG way from a reduction of risk to a recommendation of ACTION with many factors, not the least of which for the CDC is religion due to the 1st Amendment. – Russell Steen Jun 08 '11 at 19:56
  • Risk in US Navy men is a very specific subset and can't be generalized (not to mention suffering from all the flaws you claim exist in the other research). And lastly, no all the proof I listed does not rely on those three clinical trials. – Russell Steen Jun 08 '11 at 19:57
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    The fact that this answer is as upvoted as it is a travesty against science and against this site. Where big money has been put in, and where the results count, as in Africa, they *universally* find that circumcision aids against HIV risk. I wish I could downvote this answer a million times. I hate how fashionable it has become to be anti-circumcision; can you believe that these fanatics are actually thinking about banning it, even for religious purposes, in San Francisco? Now they distort science to show that they care about the supposed "human rights abuses" of circumcision. Please. – Uticensis Jun 09 '11 at 03:39
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    @Billare This answer cites a Cochrane study, pretty much the gold standard in clinical research. If this is a “travesty against science”, I don’t know what science is. You say that hate how fashionable it’s become to be anti-circumcision. But that’s completely irrelevant here. These “fanatics” you speak of oppose an unnecessary intrusive surgery in small infants. That’s just like opposing removal of tonsils or the appendix in healthy people. Which, hey, happens to be almost universal: you don’t generally perform surgery on healthy people. – Konrad Rudolph Jun 09 '11 at 09:15
  • @Darwy The answer at the moment has a huge readability problem because it has become cluttered in the course of adding more resources. It would be good if you could reorganize the salient points and prune the weed a bit. Including important results from the studies (e.g. the Cochrane report) in a summary would also help. At the moment many people won’t bother wading through the evidence, which makes @Billare’s reaction somewhat comprehensible. – Konrad Rudolph Jun 09 '11 at 09:19
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    If someone wishes to circumcise themselves based on the CDC/WHO recommendations, that's fine - it's their choice. I just feel it's a very poor policy to advocate it for the public health when there ARE significant questions regarding efficacy. – Darwy Jun 09 '11 at 09:22
  • @Konrad, @Darwy. FYI: I did some minimal tidying up, but nothing to strengthen (or weaken) the argument. – Oddthinking Jun 09 '11 at 10:31
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    @Oddthinking Thanks, I can never get the bullets to work right for me. – Darwy Jun 09 '11 at 10:34
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    @Konrad Rudolph Your "unnecessary" is a loaded word, and needs some damned strong evidence behind it before you and others go about preaching and restricting the liberties of other people to do as they wish with their own children. It is certainly "necessary" for people who derive a religious benefit out of it; it is certainly more hygienic, and in my opinion, more pleasing to the eye than the alternative; and thirdly, what the bulk of the evidence shows that it is firmly protective of HIV in undeveloped countries.... – Uticensis Jun 11 '11 at 03:50
  • and the only reason it hasn't been so shown in developed countries is because it's unimportant there, as HIV is not a general disease there, being much more particularized to certain populations who may confound the data (gays, drug users, minorities). And to be honest, though I've never heard of a Cochrane review before, I'm not in the slightest moved by this study -- it comes from a rather third-rate university (it's competitor is sponsored by the WHO/CDC), it's published in a Pub. Pol. journal (vs. PLoS One, _quite_ exacting to get into), and it's a meta-analysis (vs. a huge sample study). – Uticensis Jun 11 '11 at 03:57
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    What's more, @Darwy has actually mis-stated the conclusions of the study he links: They say, **"Despite the positive results of a number of observational studies, there are not yet sufficient grounds",** and he says, **"No. Circumcision does not reduce HIV risk."** There's a big difference between these. What they emphasize is that the protection of circumcision vs. HIV is _indeterminate_ (crock, in any case); Darwy turns that around to make the mistake that being unable to reject the null hypothesis (there is no difference between the two group) proves his Hypothesis II (no efficacy.) Tosh. – Uticensis Jun 11 '11 at 04:05
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    @Billare You make many assumptions - first that your opinion of what is 'pleasing to the eye' is shared by everyone. It isn't. Furthermore, the surgical amputation of healthy tissue is by definition, "unnecessary". Also, it was MY statement that "Circumcision does not reduce HIV risk", it wasn't the study conclusion. The studies I linked (including the Cochrane study) were supporting my statement. Finally - your gender bias is showing. – Darwy Jun 11 '11 at 07:53
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My own answer ripped straight from this question:

The CDC concludes that circumcision does reduce risk of disease based on multiple lab studies and controlled intervention trials, in addition to the statistical research that opponents focus on for "refuting" the evidence.

This is a topic where research has been done and confirmed, it boils down to this:

Research indicates reduced HIV risk for circumcised men, both in labs and in the real world (where people don't always wear condoms, for whatever reason).

References:

Basically every significant health organization in the world is behind this, entailing almost 40 different clinical trials since the 1980s and numerous lab trials demonstrating that the uncut penile tissue around an intact foreskin is more receptive to HIV infection.

Also of note, this only speaks to the risk to the male in question. It also may not apply to subsets (for any medical research you will always be able to find some subgroup of the population that has a different outcome)

Thanks to @OddThinking it appears another real world trial has been performed supporting this claim. This study directly provides real evidence against the risk compensation claim.

Three years after the voluntary medical male circumcision (MC) campaign rolled out in the Orange Farm Township in South Africa, the first “real world” results are available showing a marked reduction of HIV acquisition among circumcised adult men with a 55 percent lower HIV prevalence (proportion of HIV-infected people) among circumcised men compared to their uncircumcised counterparts and overall reduction in HIV incidence (the number of new cases) among men 15 to 34 years old of 76 percent.

Glorfindel
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Russell Steen
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According to the World Health Organization's Male circumcision for HIV prevention:

There is compelling evidence that male circumcision reduces the risk of heterosexually acquired HIV infection in men by approximately 60%. Three randomized controlled trials have shown that male circumcision provided by well trained health professionals in properly equipped settings is safe. WHO/UNAIDS recommendations emphasize that male circumcision should be considered an efficacious intervention for HIV prevention in countries and regions with heterosexual epidemics, high HIV and low male circumcision prevalence.

See also Male circumcision: a globally relevant but under-utilized method for the prevention of HIV and other sexually transmitted infections Annual Review of Medicine 2014; vol. 65 pages 293-306:

Randomized trials have demonstrated that male circumcision (MC) reduces heterosexual acquisition of HIV, herpes simplex virus type 2, human papillomavirus (HPV), and genital ulcer disease among men, and it reduces HPV, genital ulcer disease, bacterial vaginosis, and trichomoniasis among female partners.

DavePhD
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