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Observational studies

In 1989 Cameron found uncircumcised men 8.2 times more likely to have HIV. Since then over 40 epidemiological studies have been conducted to investigate the relationship between circumcision and HIV infection.

In 1994, de Vincenzi and Mertens surveyed previous studies that had links between circumcision status and HIV; they surveyed 23 in total. They criticised the Cameron study saying that it may have suffered from selection bias.

In 1995 Ntozi noted: "There are now two schools of thought about the link between lack of circumcision and HIV infection in Africa. One school is that of Bongaarts et al. (1989), Moses et al. (n.d.) and Caldwell and Caldwell (1994) who use geographical distribution evidence to argue that the association between lack of circumcision and a high level of HIV infection in Africa is so convincing that the likelihood of a link should be recognized and taken into account where possible in the battle against AIDS. Moses et al. (n.d.) have gone further to recommend circumcision interventions for Africa. In contrast, De Vincenzi and Mertens (1994) argue that the evidence for an association, at least from small-scale surveys, is doubtful and hence not conclusive enough to qualify circumcision as an intervention.

Van Howe conducted a meta-analysis in 1999 and found circumcised men at a greater risk for HIV infection. He further speculated that circumcision may be responsible for the increased number of partners, and therefore, the increased risk. Van Howe's work was reviewed by O'Farrell and Egger (2000) who said Van Howe used an inappropriate method for combining studies, stating that re-analysis of the same data revealed that the presence of the foreskin was associated with increased risk of HIV infection (fixed effects OR 1.43, 95%CI 1.32 to 1.54; random effects OR 1.67, 1.25 to 2.24). Moses et al.(1999) also criticised Van Howe's paper, stating that his results were a case of "Simpson's paradox, which is a type of confounding that can occur in epidemiological analyses when data from different strata with widely divergent exposure levels are combined, resulting in a combined measure of association that is not consistent with the results for each of the individual strata." They concluded that, contrary to Van Howe's assertion, the evidence that lack of circumcision increases the risk of HIV "appears compelling".

Weiss, Quigley and Hayes carried out a meta-analysis on circumcision and HIV in 2000 and found as follows: "Male circumcision is associated with a significantly reduced risk of HIV infection among men in sub-Saharan Africa, particularly those at high risk of HIV. These results suggest that consideration should be given to the acceptability and feasibility of providing safe services for male circumcision as an additional HIV prevention strategy in areas of Africa where men are not traditionally circumcised."

The USAID document summarised research as of September 2002. It states:

A systematic review and meta-analysis of 28 published studies by the London School of Hygiene and Tropical Medicine, published in the journal AIDS in 2000, found that circumcised men are less than half as likely to be infected by HIV as uncircumcised men. A subanalysis of 10 African studies found a 71 percent reduction among higher-risk men. A September 2002 update considered the results of these 28 studies plus an additional 10 studies and, after controlling for various potentially confounding religious, cultural, behavioral, and other factors, had similarly robust findings. Recent laboratory studies in Chicago found HIV uptake in the inner foreskin tissue to be up to nine times more efficient than in a control sample of cervical tissue.

Siegried et al. (2003) surveyed 35 observational studies relating to HIV and circumcision: 16 conducted in the general population and 19 in high-risk populations. They state:

We found insufficient evidence to support an interventional effect of male circumcision on HIV acquisition in heterosexual men. The results from existing observational studies show a strong epidemiological association between male circumcision and prevention of HIV, especially among high-risk groups. However, observational studies are inherently limited by confounding which is unlikely to be fully adjusted for. In the light of forthcoming results from RCTs, the value of IPD analysis of the included studies is doubtful. The results of these trials will need to be carefully considered before circumcision is implemented as a public health intervention for prevention of sexually transmitted HIV.

In 2005, Siegfried et al. published a review including 37 observational studies. Most studies indicated an association between lack of circumcision and increased risk of HIV, but the quality of evidence was judged insufficient to warrant implementation of circumcision as a public health measure. The authors stated that the results of the three randomised controlled trials then underway would therefore provide essential evidence about the effects of circumcision as an HIV intervention.

Kiwanuka et al.'s (1996) study on the relationship between religion and HIV in rural Uganda was presented at the 1996 10th International AIDS Conference He said that: "Lower rates of HIV infection among Pentecostals appear to be associated with less alcohol consumption, sexual abstinence and fewer sexual partners, whereas the low HIV prevalence in Muslims appears to be associated with low reported alcohol consumption and male circumcision." Muslims, despite having the lowest rate of sexual abstinence and the highest rate of having two or more sexual partners, had the lowest level of HIV infection compared with the other religious groups in the study (Catholics, Protestants, and Pentecostals). The factor in common between the Muslims (14.5% seropositive) and the Pentecostals (14.6% seropositive) was the lower alcohol consumption rate in these two groups than amongst Protestants (19.2%) and Catholics (19.9%).

Kelly et al. (1999) investigated the age of male circumcision and risk of prevalent HIV infection in rural Uganda and found that circumcision before the age of 12 resulted in a reduction to 0.39 of the odds of being infected. The degree of protection varied with the age at which circumcision was performed. Those circumcised at between 13 and 20 years had an odds ratio of 0.46, and those circumcised after the age of 20 at an odds ratio of 0.78. They concluded: "Prepubertal circumcision is associated with reduced HIV risk, whereas circumcision after age 20 years is not significantly protective against HIV-1 infection."

Buvé and colleagues (1999) investigated the reasons why the HIV prevalence rate among pregnant women in many large towns in Central, East and southern Africa was higher (>30%) than in the cities and towns of most of West Africa (<10%). Between June 1997 and March 1998 surveys were carried out and blood samples were taken in 4 sites. Kisumu (Kenya) and Ndola (Zambia), in Central/East Africa, were selected as the towns with high HIV prevalence, while the low-prevalence towns in West Africa were Cotonou (Benin) and Yaoundé (Cameroon). "In conclusion, differences in the rate of HIV spread between the East African and West African cities studied cannot be explained away by differences in sexual behaviour alone. In fact, behavioural differences seem to be outweighed by differences in HIV transmission probability."

Bailey et al. (1999) interviewed 188 circumcised and 177 uncircumcised consenting Ugandan men in one of four native languages during April and May, 1997. Non-Muslim circumcised men were found to have a higher risk profile than uncircumcised men. Muslims generally had a lower risk profile than other circumcised men except they were less likely to have ever used a condom or to have used a condom during the last sex encounter. Bailey et al. concluded that "these results suggest that differences between circumcised and uncircumcised men in their sex practices and hygienic behaviors do not account for the higher risk of HIV infection found among uncircumcised men. Further consideration should be given to male circumcision as a prevention strategy in areas of high prevalence of HIV and other sexually transmitted diseases. Studies of the feasibility and acceptability of male circumcision in traditionally non-circumcising societies are warranted."

Bonner (2001) reserved caution over using circumcision to prevent HIV: "Until we know why and how circumcision is protective, exactly what the relationship is between circumcision status and other STIs, and whether the effect seen in high-risk populations is generalisable to other groups, the wisest course is to recommend risk reduction strategies of proven efficacy, such as condom use."

At the 14th International AIDS conference in 2002, Changedia and Gilada reported that "Though circumcision offers protection in acquisition of HIV infection, our findings reveal that it does not reduce transmission of HIV in conjugal settings." Hunter et al. (1994), however, report that "Women whose husband or usual sex partner was uncircumcised had a threefold increase in risk of HIV, and this risk was present in almost all strata of potential confounding factors." Fonck et al. (2000) reported that "Partners of circumcised men had less-prevalent HIV infection."

The prevalence of circumcision varies across Africa. Studies have been conducted to assess the acceptability of promoting circumcision in place where they traditionally do not circumcise. In 2007, country consultations and planning to scale up male circumcision programmes took place in Botswana, Kenya, Lesotho, Malawi, Mozambique, Namibia, Rwanda, South Africa, Swaziland, Uganda, Tanzania, Zambia andZimbabwe. Kebaabetswe et al. carried out interviews in nine geographically representative locations to determine the acceptability of male circumcision as well as the preferred age and setting for male circumcision in Botswana. Their conclusion was "Male circumcision appears to be highly acceptable in Botswana. The option for safe circumcision should be made available to parents in Botswana for their male children. Circumcision might also be an acceptable option for adults and adolescents, if its efficacy as an HIV prevention strategy among sexually active people is supported by clinical trials." Boyle criticised Kebaabetswe et al.'s proposal to introduce infant circumcision to Botswana saying that: "The proposal by Kebaabetswe and colleagues for the introduction of circumcision into Botswana is seriously flawed, and is irresponsible in failing to place the emphasis on safe sex practices. As described here, there are many medical, sexual, psychological, social, human rights, ethical, and legal aspects that must be considered. Reliance on circumcision to prevent HIV transmission is wishful fantasy, and can only result in a calamitous worsening of the HIV-AIDS epidemic."

Bailey et al. looked at the possible adverse effects of introducing male circumcision on a public health scale and the post operative satisfaction levels of 380 circumcisions on 18-24 year old consenting men. As to satisfaction; "At 30 days post-surgery, 99.3% of men reported being very satisfied and 0.7% somewhat satisfied with circumcision. None were dissatisfied." And with regard to adverse effects; "All were mild or moderate and resolved within hours or several days of detection." Their findings were presented at the 15th International AIDS Conference held in Bangkok in 2004.

At the 15th International AIDS Conference in 2004, Connolly et al. presented their report detailing the effects of circumcision in South Africa. They reported that, among racial groups, "circumcised Blacks showed similar rates of HIV as uncircumcised Blacks, (OR: 0.8, p = 0.4) however other racial groups showed a strong protective effect, (OR: 0.3, p = 0.01)." They added "When the data are further stratified by age of circumcision, there is a slight protective effect between early circumcision and HIV among Blacks, OR: 0.7, p = 0.4." They conclude that "in general, circumcision offers slight protection." At the same conference, Thomas et al. (2004) reported that "male circumcision is not associated with HIV or STI prevention in a U.S. Navy population."

Reynolds et al. (2004) found that male circumcision was strongly protective against HIV-1 infection with circumcised men being almost seven times less at risk of HIV infection than uncircumcised men. They further state that: "The specificity of this relation suggests a biological rather than behavioural explanation for the protective effect of male circumcision against HIV-1."

Baeten et al. (2005) found that uncircumcised men were at a greater than twofold increased risk of acquiring HIV per sex act when compared with circumcised men. They conclude as follows:

"Moreover, our results strengthen the substantial body of evidence suggesting that variation in the prevalence of male circumcision may be a principal contributor to the spread of HIV-1 in Africa."

At the 2006 Conference on Retroviruses and Opportunistic Infections Quinn et al. presented their study, conducted in Rakai, Uganda, which observed a 30% reduction in male-to-female HIV transmission, suggesting some protective effect for the female partner.

Newell and Bärnighausen (2007) also stated there was "firm evidence that the risk of acquiring HIV is halved by male circumcision."

Mishra et al. (2006) used data collected from the Demographic and Health Surveys and found that HIV prevalence was "considerably higher in urban areas and for women, especially at younger ages. Adults in wealthier households, in polygamous unions, being widowed/divorced/separated, having multiple sex partners, and having reported STIs had higher HIV rates than other adults. No consistent relationship between male circumcision and HIV risk was observed in most countries."

Way et al. (2006) also used data from Demographic and Health Surveys in Burkina Faso, Cameroon, Ghana, Kenya, Lesotho, and Malawi and from AIDS Indicator Surveys in Tanzania andUganda to conduct his study. They found that "With age, education, wealth status, and a number of sexual and other behavioral risk factors controlled statistically, in only one of the eight countries were circumcised men at a significant advantage. In the other seven countries, the association between circumcision and HIV status was not statistically significant for the male population as a whole."

Garenne (2006) has doubts about circumcision's value in reducing HIV, and Talbott (2007), in a controversial paper stated that cross country regression data pointed to prostitution as the key factor in the AIDS epidemic rather than circumcision. World Health Organization AIDS Prevention Team official Tim Farley disagreed with the findings of the paper, while Chris Surridge, PLoS One's managing editor, defended its publication. In 1999 the American Medical Association had stated, "behavioral factors are far more important in preventing these infections than the presence or absence of a foreskin."

If proper hygienic procedures are not adhered to, the circumcision operation itself can spread HIV. Brewer et al. (2007) report, "[circumcised] male and female virgins were substantially more likely to be HIV infected than uncircumcised virgins. Among adolescents, regardless of sexual experience, circumcision was just as strongly associated with prevalent HIV infection. However, uncircumcised adults were more likely to be HIV positive than circumcised adults." They concluded: "HIV transmission may occur through circumcision-related blood exposures in eastern and southern Africa."

Van Howe et al. criticise the drive to promote circumcision in Africa, asking "Why are circumcision proponents expending so much time and energy promoting mass circumcision to North Americans when their supposed aim is to prevent HIV in Africa? The circumcision rate is declining in the US, especially on the west coast; the two North American national paediatric organisations have elected not to endorse the practice, and the practice’s legality has been questioned in both the medical and legal literature. ‘Playing the HIV card’ misdirects the fear understandably generated in North Americans by the HIV/AIDS pandemic into a concrete action: the perpetuation of the outdated practice of neonatal circumcision."

Connolly et al. (2008) found that "circumcision had no protective effect in the prevention of HIV transmission. This is a concern, and has implications for the possible adoption of the mass male circumcision strategy both as a public health policy and an HIV prevention strategy."

Sidler et al. (2008) say that using neonatal non-therapeutic circumcision to combat the HIV crisis in Africa is neither medically nor ethically justifiable. Furthermore, promoting circumcision might worsen the problem by creating a false sense of security and therefore undermining safe sex practices. Education, female economic independence, safe sex practices and consistent condom use are proven effective measures against HIV transmission.

Boiley et al. (2008) found that the protection of circumcision against STI contributes little to the overall effect of circumcision on HIV.