A study called Circumcision and Reduced Risk of Self-Reported Penile Coital Injuries published in the Journal of Urology recently looks at whether circumcision reduces the incidence of injuries to the penis during sex, which may increase the risk of HIV infection. It found that the incidence of injury was less in circumcised than uncircumcised men.
Between 2002 and 2005, 2,784 men aged between 18 and 24 in Kisumu, Kenya were randomized into two groups, immediate circumcision and delayed circumcision after two years.
Injuries were classified as 1) penis feels sore during sex 2) penis gets cuts, scratches or abrasions during sex and 3) penis bleeds after sex. At the start of the two-year period, 64.4% of the men reported injuries and 10.5% reported all three. Having two or more sex partners in the last 30 days, applying substances to the penis before sex and having ulcers increased the risk of injury. Increased age was associated with increased risk, possibly because of 'a broader range of sexual practises'.
Any conclusion that circumcision in itself reduces injury risk is not substantiated by the research, however.
Both groups had intensive STI and HIV risk reduction counseling and were provided with unlimited free condoms. The prevalance of STIs decreased, condom use increased and reporting multiple sex partners decreased. After two years, it was found that circumcision, condom use, being married or living with a partner and cleaning the penis within one hour of sex reduced injury.
At the beginning, the 64.4% reporting injuries split into 65.1% of circumcised and 60% of uncircumcised men. After two years, 31% of circumcised men and 42.8% of uncircumcised still reported injuries.
A few points:
The incidence of injury was almost the same in circumcised and uncircumcised men at the start of the trial which would suggest that it was something else that happened during the trial that caused the reduction.
The groups were not divided into men having sex with men and with women. The assumption is that all of the men's partners were female.
Injuries and sexual practices were self-reported. The types of sexual practice were not recorded. There was no enquiry into why injuries were so high to begin with or how conselling may have influenced sexual practices - or the self-reporting of them - although the conclusion admits the need to verify the injuries and questions whether familiarity with study questions may have had an influence. Why the injuries were not verified during a trial based on counting them and why familiarity was not factored in at the start are not clear if they were going to undermine the findings. It is also not possible to separate out the effects of counselling and condoms.
50% of circumcised men reporting injuries at the start were still reporting injuries at the end of the trial which suggests that other factors are involved in injury reduction.
There's a bit of an anomaly in the table showing condom use. At the start of the trial, 1010 men hadn't used condoms at their last sexual encounter; by the end of the trial, this had fallen to 259. However, 765 had used a condom the last time they had sex but two years later, this number had fallen to 275 so overall, the number of men using condoms had fallen.
Another point the research raises is that 'the high frequency of coital injuries in uncircumcised men could place sex partners of HIV positive uncircumcised men at greater risk for HIV acquisition'. However, even if circumcision does protect men, there is no good evidence yet that it helps prevent transmission from HIV positive men to women. A trial in Uganda reported in The Lancet found that rates of transmission to women increased with circumcised men. The trial had to be abandoned for ethical reasons.
The research concludes that 'circumcision, condom use and penile hygiene provided protection against reported penile coital injuries. (...) The mechanisms by which circumcision confers protection against penile coital injuries remains unknown'.
It also states that 'recent circumcision did not increase penile coital injury risk' and this is about all that it can be said to have found. Condoms, reducing the number of partners, counselling and washing are all said to reduce injury but circumcision in itself has not been demonstrated to do so independently of these other factors. Too many variables.
Evidence against circumcision for HIV prevention and the risks involved here, here and here.
UPDATE: An interesting comment on this article from Lay Science:
The big drop in injuries for both groups after six months in the study is a sign of the Hawthorne Effect - just going in a study makes a difference. The difference between the two groups after that has been excluded is relatively small.
They don't seem to mention the commonest penile injury to intact men, torn frenulum ("banjo string"). This usually happens once in a lifetime, if at all. It is hardly surprising if having a sensitive moving part on one's penis might make it (slightly) more prone to injury. Circumcision as a way to reduce penile injuries is not indicated.
This is only the latest in a steady stream of papers originating from the same few researchers (Daniel Halperin, Robert Bailey, Ronald Gray, Stefan Bailis, Stephen Moses, Malcolm Potts, Thomas Quinn, Maria Wawer, Helen Weiss, Brian Morris, Jeffrey Klausner, Edgar Schoen and Thomas Wiswell - in this case, Bailey) claiming to show that circumcision is good for everything and harms nothing. I wouldn’t call it a “conspiracy”, but many of them have authored papers jointly, and their common interest seems to be in promoting circumcision, rather than any particular benefit.