Considerable research has focused on addressing unprotected anal intercourse among men who have sex with men (MSM) as a significant risk factor for HIV and sexually transmitted infections (STIs), given that MSM bear the overwhelming burden of the U.S. HIV epidemic.^1–4 Research on heterosexual behaviors associated with acquisition of STIs, including HIV, however, has almost exclusively focused on vaginal intercourse.^{5, 6} Nonetheless, given that most women living with HIV in the U.S. were infected due to sexual contact with a high-risk male heterosexual, anal intercourse has increasingly been recognized as an area of relevant research inquiry.^7–10

National estimates from NSFG indicate 36% of women aged 25-44 report ever having had anal intercourse,¹¹ and studies have found up to 10% of heterosexual men and women did so in the previous year.¹² In one study, 38% of heterosexual women from high-risk areas in New York reported unprotected anal intercourse in the past year (n=436).³ Additionally, increasing evidence suggests that anal intercourse may be part of a repertoire of normative sexual behavior among adolescents and young adults.¹³

Unprotected receptive anal intercourse is a particularly efficient method for HIV (and other STI) transmission when compared to vaginal intercourse for women^{3, 6, 13–17} due to increased likelihood of mucosal disruption and trauma within the rectum compared to the vaginal lining.^{3, 18} The estimated probability for HIV infection per act of unprotected receptive anal intercourse is 5 times that per act of unprotected vaginal intercourse.^{3, 19, 20}

The risk associated with anal intercourse is compounded by infrequent condom use by heterosexual adults and adolescents for anal intercourse when compared to vaginal intercourse, and when compared to anal intercourse among MSM. Studies have also highlighted the absence of pregnancy risk and poor understanding of the STI/HIV risks associated with anal intercourse as factors contributing to infrequent condom use.^{5, 7, 9, 13, 21}

Recent research also has focused on developing a better understanding of the factors associated with inconsistent condom use and problems during use (i.e., breakage, slippage, or partial use [delayed application or early removal]) among U.S. men who have sex with men.^{4, 22–25} In our previous examination of condom use for receptive and insertive anal intercourse within a sample of MSM STD clinic patients, in nearly half (43%) of partnerships condoms were not used, and another 11% involved only inconsistent use.²⁶ Inconsistent condom use for anal intercourse among MSM has been associated with beliefs that pre-ejaculatory fluid poses no or minimal risk for HIV/STI transmission or that only rectal trauma poses HIV risk resulting in the false sense of security that brief penetration without protection is a safe behavior.^{22, 23} Further, MSM report heightened perceived risk for HIV/STIs and more consistent condom use within non-main partnerships.^{26, 27}

In the present analysis, we examined individual respondent, partner, and partnership-related factors among women and MSM that influence the decision to use condoms during receptive anal intercourse. Specifically we: 1) determined the prevalence of receptive anal intercourse in a sample of urban U.S. STD clinic patients; 2) assessed differences in condom use consistency for receptive anal intercourse only among heterosexual women and MSM; and 3) examined characteristics and cognitive factors associated with condom use consistency for receptive anal intercourse and how these factors differ for women and MSM.

Data were analyzed from the Safe in the City behavioral study, a nested component of a larger trial evaluating the effects of a video-based waiting room intervention modeling couples overcoming barriers to safer sexual behaviors on STI incidence among patients (N=38,635) attending participating clinics.²⁸

Of 1609 STD clinic patients participating in the behavioral study of the Safe in the City trial, there were 555 women and 263 MSM who were included for current analysis. Among female respondents, most had at least a high school education, had never been married, and were Hispanic or black (Tables 2 & 3). Most MSM respondents similarly had a high school education, though the majority was white. Women reported a total of 1436 sexual partnerships, and MSM reported 765 sexual partnerships. Approximately 31% of women and 70% of MSM reported receptive anal intercourse at least once in the past 3 months. Overall, women reported receptive anal intercourse within 254 (17.7%) partnerships, and MSM within 425 (55.6%) partnerships. Of female partnerships where receptive anal intercourse occurred, 195 partnerships (76.8%) involved inconsistent/nonuse of condoms for receptive anal intercourse, whereas condoms were used consistently in 59 (23.2%) partnerships. Of MSM partnerships where anal intercourse was reported, inconsistent/nonuse of condoms for receptive anal intercourse occurred in 233 (54.8%) partnerships whereas consistent use was reported in 192 (45.2%) partnerships. The percentage of partnerships with consistent condom use during receptive anal intercourse was significantly higher in MSM compared to women (chi-square=32.87, p<0.0001). (Table 3)

Bivariate analyses identified a number of individual, partner- and partnership-specific variables that were associated with consistent condom use during receptive anal intercourse separately for women and MSM, and female and MSM partnerships. (Tables 2 & 4)

Almost one-third of female and nearly three-quarters of MSM participants in the Safe in the City trial reported engaging in receptive anal intercourse during the preceding 3-months. Consistent condom use during receptive anal intercourse was significantly lower for female respondents than MSM respondents. However, even among MSM, consistent condom use for receptive anal intercourse was less than optimal. We have previously reported inconsistent condom use among MSM who participated in the Safe in the City evaluation for all anal intercourse (insertive and receptive), highlighting HIV/AIDS-related morbidity and mortality and the prevention efforts targeted to this group.²⁶ Overall, these results suggest that innovative efforts to increase consistent condom use by MSM are needed.

Our findings provide additional information about cognitive factors that influence decisions to use condoms during receptive anal intercourse. Factors associated with consistent condom use during receptive anal intercourse differed markedly between women and men who have sex with men, with three exceptions: intention to use condoms with all partners, partner support for condom use, and the belief that the partner did not give the respondent an STI. Thus, intervention efforts focused on increasing condom use intention with all partners and strategies for developing partner support for condom use may be beneficial for both groups. The fact that condom use was associated with believing one’s partner had not given the respondent an STI is possibly attributable to the fact that data were collected retrospectively. In the cases where respondents used condoms consistently with a particular partner, they likely believed they were not at risk for contracting an STI from that partner due to the perceived effectiveness of the condom.

Unique to women was the ability to discontinue sex when a condom was not available, which was significantly associated with consistent use for anal intercourse. Thus, emphasizing skills-based condom use counseling that focuses on delayed gratification techniques may be beneficial, as condoms may not always be available. For MSM, condom use self-efficacy in the partnership was significantly predictive of consistent use during receptive anal intercourse, which underscores the importance of context of sexual partnerships when promoting condom use strategies. The finding that condoms were used more consistently with non-main partners by MSM has been previously reported in the literature.²⁷

There are some limitations to our findings. First, the present analysis relied on self-reports of receptive anal intercourse from the prior 3-months. Although this time frame has been employed for evaluating anal intercourse in other studies,^28–30 it may be subject to error particularly among individuals who engage in anal intercourse repeatedly with multiple partners. Further, there are limitations inherent within studies that rely on self-reported behavioral data for recall of sensitive behaviors, particularly during studies of HIV/STI behavioral interventions. Another potential limitation is that the Safe in the City trial was conducted approximately 10 years ago. However, more recent studies continue to affirm that consistent use for anal intercourse remains a public health priority as women and MSM continue to use condoms infrequently for receptive anal intercourse, even with high risk partners.¹⁰ Finally, our results may not be generalizable to all women or MSM outside of the STD clinic setting or, including HIV-positive patients who were excluded from the Safe in the City trial.

Anal intercourse has rarely been discussed openly in health care or research settings as an HIV risk factor for heterosexual women likely due to cultural taboos and stigma resulting from its association with homosexuality and the perception that it represents unhygienic behavior.^{6, 21} Several public health practice recommendations emerge from this work. First, given that a high proportion of persons attending STD clinics reported recent anal intercourse, clinicians should screen patients for exposure in the past 3 months, and consider screening patients for infection. The U.S. Center for Disease Control and Prevention recommends screening persons at risk for rectal chlamydial or gonococcal infection. Second, sexual health education and disease prevention programs should include a discussion of anal intercourse, its role in health and disease transmission, and opportunities to reduce the risk of HIV and STI transmission during anal intercourse with interventions such as routine screening for infection, condom use, use of lubricants and pre-exposure prophylaxis (PrEP). Condom use counseling should consider barriers and facilitators unique to receptive anal intercourse and tailored to aspects of particular sexual partnerships such as those shown to be associated with consistent condom use in our study for each population. For example, our findings suggest that improving self-efficacy for condom use and the ability to effectively discuss the need for condom use during anal intercourse with a partner may help facilitate condom use for both women and MSM. Finally, more research is needed to better understand motivations for anal intercourse among heterosexual men, women, and MSM, as those findings might inform prevention interventions.