A U.S. male has a 1.87% chance of becoming infected with HIV over his lifetime, and the risk varies substantially by race and ethnicity, from 0.94% among white males to 6.22% among black males. Using randomized clinical trial results from Africa, our analysis shows that newborn circumcision can reduce the lifetime risk of HIV, and that the protective effect also varies by race/ethnicity. The reduction is 16% for all males, nearly 21% for black males, and 8% for white males, given the base case assumption that the protective effect of circumcision applies only to heterosexually acquired HIV.
Our analysis indicates that racial and ethnic groups who would potentially benefit the most from newborn circumcision because they are at greater risk of HIV transmission through heterosexual contact, currently, have a lower prevalence of circumcision than white males. Circumcision prevalence was 73% for black males and 42% for Mexican American males, compared with 88% among white males 
. Based on our estimated number needed to treat and the 2006 male birth cohorts for blacks (314,670), Hispanics (530,971), and whites (1,184,120), if the entire racial/ethnic cohort were circumcised instead of the proportions reported above, then 1,307 HIV infections would be prevented among the cohort of black males, or 6.7% of those expected over their lifetimes, 1,149 (7.5%) cases would be prevented among Hispanic males, and 115 (1.0%) of those expected among white males. 
Parents, in consultation with their physician, family members and other health care professionals, decide whether newborn circumcision is performed, and these decisions often are made based on religious or cultural grounds. The decision may be constrained, however, by health care reimbursement policies. In a 1995 review, 61% of circumcisions were paid for by private insurance, 36% by Medicaid, and 3% by the parents 
. In 1999, the American Academy of Pediatrics revised its policy on newborn circumcision to state that “existing scientific evidence demonstrates potential medical benefits of newborn male circumcision; however, these data are not sufficient to recommend routine neonatal circumcision 
.” Currently, a number of states have eliminated Medicaid payments for circumcisions not deemed medically necessary 
. In states whose Medicaid program covers neonatal circumcision, rates were reported to be more than twice as high (69.6%) as in states whose Medicaid program does not pay for male circumcision (31.2%) 
. In these latter states, populations most likely to benefit from newborn circumcision may be least able to obtain it. In 2005, 40% of Hispanic children and 46% of black children were covered by Medicaid, compared with 19% of white children 
Our results show that newborn circumcision is usually cost saving in the United States because of the low cost of the procedure, current lifetime risk of HIV among U.S. males and the high cost of treating HIV. Previous economic evaluations of newborn circumcision in the U.S. were published before data on HIV prevention from the African trials became available. Those studies typically focused on costs and benefits of circumcision-associated conditions other than HIV and other STIs. Even when these benefits were included, the magnitude of the benefit and the lifetime HIV risk among males were not as well understood. One study found the expected lifetime cost of circumcision was small, compared with larger expected benefits 
. Two of the studies estimated that both costs and benefits were too small to play an influential role in the decision whether to perform the procedure 
. One study found that negative outcomes associated with circumcision outweighed the benefits 
Newborn circumcision for white males in the United States did not generate cost-saving results. White males already have a high prevalence of circumcision (88%), a low lifetime risk of HIV (0.96%) and a low risk of acquiring HIV through heterosexual contact (6.7%) compared with black and Hispanic males, so additional circumcisions provide little benefit. The incremental cost-effectiveness ratio for the base case analysis for white males was $87,792. A probabilistic sensitivity analysis showed that the incremental cost-effectiveness ratio fell below $150,000 67.3% of the time and below $200,000 82% of the time. Historically, a common cost-effectiveness threshold in the U.S. has been $50,000 per quality-adjusted life-year saved. A more recent analysis of society's current willingness to pay for an extra year of life suggested a range of $183,000 to $264,000 
. Others have suggested a threshold approaching $200,000 or more 
. The World Health Organization considers a country-specific threshold equal to three times the country's per-capita gross domestic product 
. In 2007, the U.S. per capita gross domestic product was $46,800, or $140,400 when tripled 
The choice of discount rate had the biggest effect on the incremental cost-effectiveness ratio. The impact of discounting is particularly large in this analysis because the intervention costs are assumed immediately at birth, but the prevention benefits do not begin to accrue until more than three decades later. In our base case, we used the recommended 3% discount rate 
. Further guidance on how best to discount benefits that occur in adulthood following interventions delivered in childhood would be helpful.
Other important factors in the one-way sensitivity analysis were lifetime efficacy of circumcision in preventing heterosexually-acquired HIV and the cost of newborn circumcision. However, even the least favorable inputs generated cost-effective results for all males. Nonetheless, more research on the long-term efficacy of circumcision would be useful.
We note that even a modest efficacy in preventing HIV transmission among MSM makes the procedure more cost-effective. For white males, an efficacy of 5% improves the cost-effectiveness ratio from $87,792 in the base case to $37,402. An efficacy of 20% makes the procedure cost saving for white males. Currently, there are no data from randomized clinical trials on the benefits of circumcision in preventing HIV among MSM. These data would be useful in determining the impact of newborn circumcision on HIV epidemics in developed countries where a significant number of HIV infections occur through sex among MSM.
Our analysis has two limitations that, if considered, would make neonatal circumcision more cost-effective. First, our analysis did not include other health benefits associated with the procedure. Lack of male circumcision has been associated with increased incidence of sexually transmitted ulcer disease, infant urinary tract infections, penile cancer, and cervical cancer in the female partners of uncircumcised men 
. One meta-analysis of the association between male circumcision and risk of genital ulcer disease concluded that there was a significantly lower risk of syphilis and chancroids among circumcised men but less effect on HSV-2 
. Further analyses of the randomized, controlled circumcision trial in Uganda found a 28% decreased cumulative probability of HSV-2 over 24 months and a lower prevalence of high-risk HPV genotypes, but no significant difference in the incidence of syphilis among circumcised trial participants compared with those who were not circumcised 
. Subsequent multivariate analyses of the South African trial data found a 34% decrease in the incidence of HSV-2 over 21 months among circumcised compared with uncircumcised males 
Second, we did not count secondary HIV transmissions that would be prevented among partners of circumcised males who remained uninfected due to circumcision. Models showing the benefits of circumcision in Africa indicate benefit to female partners over time as HIV prevalence among men declines 
We did not include two factors that could make neonatal circumcision for HIV prevention less cost-effective. One was the cost of adverse events associated with newborn circumcision. In large studies of newborn circumcision in the U.S., complication rates ranged from 0.2% to 2%, most commonly minor bleeding and local infection 
. Another study found a complication rate of .22% (mostly bleeding) among newborns who were circumcised before discharge from the hospital, compared with .01% among those who were not circumcised. The circumcised newborns with complications had an average hospital stay of 2.81 days compared with 2.26 days among those circumcised but without complications 
Also, we did not attempt to model potential changes in risky sexual behaviors among circumcised men. The South African circumcision trial showed that men in the intervention group had significantly more sex acts (but not partners) over the course of the trial, although the protective effect of circumcision remained 
. The Kenyan and Ugandan trials reported that circumcised men did not practice riskier sexual behaviors during those trials 
. In Kenya, risk behaviors among circumcised and uncircumcised men declined over a 12-month period during the trial 
. As the benefits of circumcision in preventing heterosexually acquired HIV become more widely known, circumcised men and their partners may practice riskier sexual behaviors. On the other hand, men who have been circumcised since birth may be less likely to take their circumcision status into account when determining the level of risk acceptable to them and their partners. Sexual risk practices should be monitored over time through surveys and safe sex practices should continue to be encouraged among circumcised males and their partners.
We based our analysis on current estimates of lifetime HIV risk, HiV transmission categories, circumcision prevalence, and costs of both newborn circumcision and lifetime HIV treatment. These estimates could change in ways that might make neonatal circumcision more or less cost-effective over the lifetime of a male born today.
Although our study accounted for the differences U.S. and African males in HIV and circumcision prevalence and mode of HIV transmission, we assumed the protective effect of circumcision observed in the African trials was applicable to U.S. males. The efficacy of circumcision in all three of the randomized African trials, which occurred in three different countries, was remarkably similar. Randomizing participants to immediate or delayed circumcision is likely to have controlled for other factors that would have made HIV acquisition more or less likely to occur in the intervention versus the control groups. It is possible that the protective effect of circumcision in the African trials was due to the prevention of HSV-2, which then prevented the acquisition of HIV, and so the protective effect of circumcision in the United States would be reduced because of the lower HSV-2 prevalence among U.S. males. However, investigators from the South African trial reported that the protective effect of circumcision appeared to be independent of HSV-2 serostatus. Moreover, the prevalence of HSV-2 among the South African trial participants was similar to that among U.S. males 
. Investigators from the Ugandan trial reported that genital ulcer disease played at most a modest role in the protection of HIV afforded by circumcision 
. Thus, while the absolute incidence of HIV observed among heterosexual men in the African trials is much larger than that among U.S. heterosexual males, we assumed the relative 60% decrease in heterosexual transmission among circumcised compared with uncircumcised males would hold true regardless of the underlying prevalence of HIV, circumcision or HSV-2.
This paper evaluates the efficacy of newborn circumcision solely in the prevention of HIV, and it indicates that the procedure is cost saving under most scenarios. The greatest risk reduction occurs for black and Hispanic males. Although our analysis suggests that newborn circumcision will not have a large impact on the HIV epidemic in the United States, it could play a role in reducing the number of new cases of HIV; particularly when used with other efficacious prevention interventions. Considering variations in lifetime risk of HIV and circumcision prevalence among racial and ethnic groups in the U.S., newborn circumcision may provide one additional tool in reducing longstanding disparities in HIV incidence 
. Financial barriers that prevent parents from having the choice to circumcise their male newborns should be reduced or eliminated.