As late as 1991, heterosexual anal sex was rarely mentioned in the scientific literature as a factor in the transmission of sexually transmitted diseases (STD) including human immunodeficiency virus (HIV).1 When heterosexual anal sex was discussed, its prevalence among heterosexuals and its role in heterosexual transmission of HIV was debated1; however, in the late 1980s, studies began to identify heterosexual anal sex as a factor in male-to-female transmission of HIV.2 In fact, studies found that the risk of transmission of HIV was higher for anal sex than for vaginal sex.1
Over the past decade or so, studies of heterosexual populations at high-risk for STD/HIV have highlighted the importance of anal sex in HIV transmission3–4 and its association with STD-related outcomes such as anal cancer.5 Additionally, studies have demonstrated that a substantial percentage of heterosexuals engage in anal sex with an opposite-sex partner.6–10 More recently, research has demonstrated an increase in the proportion of heterosexuals who report engaging in heterosexual anal sex in the United States and in the United Kingdom.6,11–13 However, when considering the large body of research devoted to STD/HIV, heterosexual anal sex is often neglected as a predictor of STD/HIV and as an outcome in STD/HIV prevention intervention studies. The omission of specific questions on anal sex can result in an exclusion of anal sex partners in survey questions focusing on sex partners. Specifically, in one study, nearly 1 in 5 college students did not consider anal intercourse or anal sex partners when asked if they “had sex.”14 Although cultural issues may interfere with an interviewer’s or health care provider’s willingness to ask research participants or patients about anal sex,1,15 newer technologies such as audio computer assisted self-interview can be used to offset any discomfort.
In this issue of the journal, Tian et al.16 describe the frequency and correlates of heterosexual anal sex and associated condom use over the course of a year in STD clinic attendees from 3 US cities (Denver, Long Beach, Newark). The authors conduct a secondary analysis of data from a randomized controlled trial (RCT) that compared rapid HIV counseling and testing to standard HIV counseling and testing (RESPECT-2). All participants in the RCT received a brief counseling intervention and were followed at 3-month intervals for 1 year.17 Tian et al.16 found that many people in this high-risk population engaged in heterosexual anal sex during the year that they were followed and many engaged in the behavior fairly frequently. At baseline, 22% of respondents reported engaging in heterosexual anal sex; anal sex was also reported during 18% of the 3-month intervals.16 Of those respondents who reported engaging in heterosexual anal sex, approximately 1 in 4 had anal sex 4 or more times in a 3-month period. Additionally, 39% of respondents had heterosexual anal sex at least once in the past 12 months, and nearly 1 in 4 reported anal sex in at least 2 of the 3-month intervals. Although it was an admittedly small sample size, men who had sex with both men and women (n = 23), were more likely to report anal sex with female sex partners than men who had sex with females only. The extent to which the “bisexual bridge” has a role in STD/HIV transmission may be decreasing in some areas18; however, these findings suggest a pattern of risk that could leave some sex partners at increased risk of acquiring an STD including HIV.
Similar to previous research, Tian et al.16 examined the correlates of heterosexual anal sex at the level of the individual participant and identified a cluster of sexual risk taking (e.g., multiple sex partners, exchanging sex for money) in those who also report heterosexual anal sex; however, the authors also examined heterosexual anal sex at the level of the sexual partnership. At the partnership level, heterosexual anal sex was higher with a main partner and in partnerships where one partner was high on drugs or alcohol during sex in the past 3 months; however, heterosexual anal sex was as likely to occur in a new partnership as it was in an established partnership. Contrary to previous research on the US general population,19 demographic factors including age, sex and race/ethnicity were not related to heterosexual anal sex. Adolescents and blacks, 2 groups that are disproportionately affected by several STDs, were as likely as other subgroups to engage in heterosexual anal sex.
Finally, Tian et al.16 found that condom use for heterosexual anal sex was low; this finding is supportive of previous research.8–9,19 Condoms were not used for majority of episodes of heterosexual anal sex–63% of participants never used condoms for anal sex and only 28% of those who engaged in heterosexual anal sex consistently used condoms during anal sex. Respondents who reported using condoms for heterosexual anal sex were more likely to have 2 or more recent partners and to consistently use condoms for vaginal sex. Contrary to previous research on the US general population,19 demographic factors including age, sex and race/ethnicity were not related to condom use for heterosexual anal sex.
Clearly, this study provides additional evidence that the practice of heterosexual anal sex is occurring in persons who are already at high risk for STD/HIV and, even more importantly, the current study demonstrates that heterosexual anal sex is not simply a one-time occurrence.16 Those who engage in heterosexual anal sex do so an average of almost 5 times in a 3-month time frame with most of these acts being unprotected sex acts. Although is it somewhat encouraging (from an at-risk point of view) that persons are more likely to engage in heterosexual anal sex with a main partner compared with a casual partner, those who do so are also more likely to have multiple sex partners in a short period of time (3 months). The number of reported vaginal sex acts was much higher than those for heterosexual anal sex; however, research has estimated that the risk of HIV transmission per sex act for receptive anal sex is 5 times as high as that of receptive vaginal sex.20
Additionally, it is worth reiterating that all participants in the current study received a brief counseling intervention.17 It is possible that respondents would have reported higher rates of heterosexual anal sex or lower condom use for anal sex if they did not receive any counseling. Conversely, it is possible that unless counseling and other prevention interventions specifically mention anal sex as a risk factor for STD/HIV that some participants may not think about ways in which they can reduce their STD/HIV risk via heterosexual anal sex. To prevent potential unintended consequences from our interventions, public health researchers and practitioners should include a discussion of all types of sexual risk and protective behaviors.
Given that heterosexual anal sex is occurring with some frequency within a substantial percentage of high-risk individuals, it is worth considering if this behavior is part of an expanding sexual repertoire, a concept that was recently discussed by Foxman, et al.21,22 and could also include oral sex and group sex. At a minimum, public health researchers should consider continual monitoring of the prevalence of anal sex, the frequency with which it occurs, and associated condom use in high-risk and the general population. Although it is possible that the recent increases in reports of heterosexual anal sex are related to the use of technology such as audio computer assisted self-interview, studies with consistent data collection methods and populations have demonstrated a significant increase in the behavior.6 In 2007, CDC began collecting information on heterosexual anal sex partners in the past year in the general population using the National Survey of Family Growth. Along with data on the number of recent sex partners, concurrent partnerships, exchange sex, and condom use (vaginal, anal, and oral sex), the collection of information on heterosexual anal sex will provide public health researchers and practitioners with useful information on a more complete profile of sexual risk behaviors.
Finally, the findings from Tian et al.16 have additional implications for STD/HIV prevention research and practice. We should be sure to include appropriate information on the risks of heterosexual anal sex (and oral sex) in our STD/HIV prevention efforts. To more comprehensively assess the effects of our prevention interventions, it would be beneficial to include questions on anal sex (and unprotected anal sex) as part of surveys evaluating our STD/HIV prevention in heterosexual populations. Additionally, health care providers should consider including questions about anal sex (insertive and receptive) in a standard STD/HIV risk assessment for all patients.
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