Marks, Gary PHD*; Millett, Gregorio A. MPH*; Bingham, Trista PHD†; Lauby, Jennifer PHD‡; Murrill, Christopher S. PHD§; Stueve, Ann PHD¶
From the *Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia; †HIV Epidemiology Program, Los Angeles County Department of Public Health, Los Angeles, California; ‡Philadelphia Health Management Corporation, Philadelphia, Pennsylvania; §New York City Department of Health and Mental Hygiene, New York, New York; and ¶Education Development Center, Inc, New York, New York
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.
Correspondence: Gary Marks, PhD, Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, 1600 Clifton Road, MS: E-45, Atlanta, GA 30333. E-mail: firstname.lastname@example.org.
Received for publication July 6, 2009, and accepted September 21, 2009.
Serosorting and strategic positioning are 2 harm-reduction strategies used by some men who have sex with men (MSM) to potentially lower their risk of contracting or transmitting HIV infection. Serosorting is the practice of limiting unprotected sexual activity to partners of the same serostatus.1–3 Strategic positioning involves using the insertive or receptive role during unprotected anal intercourse (UAI) to reduce risk within serodiscordant partnerships.2,4 Thus, HIV-negative men may adopt a strategy of only engaging in the insertive position, which carries less risk than the receptive position for contracting infection.5
The protective value of these strategies has been hotly debated.2–4, 6–10 Studies have shown that some MSM do not know their own serostatus and may guess the serostatus of sex partners,6,9 thus promoting risk of infection in sexual partnerships mistakenly perceived to be seroconcordant. Other studies have shown that HIV infection risk was higher among self-reported HIV-negative MSM who serosorted8,10 or engaged in strategic positioning10 compared with MSM who did not engage in unprotected anal sex. Infection risk was lower, however, among serosorters compared with those who did not limit their UAI to partners perceived as HIV-negative8,10 and among MSM who practiced strategic positioning compared with those who did not.10
Little is known about the prevalence and protective value of serosorting and strategic positioning among black and Latino MSM, 2 groups that have been disproportionately affected by the HIV epidemic in the United States.11 We examined these harm-reduction behaviors among black and Latino MSM who self-reported that their most recent HIV test was negative. After collecting these self-reports, the men were tested for HIV infection and we calculated the percentage that tested HIV-positive among those who engaged in these harm-reduction behaviors and among those who did not.
This cross-sectional study (“Brothers y Hermanos”) was conducted in 2005–2006. Latino MSM were recruited in Los Angeles County (n = 565) and New York City (n = 516), and black MSM were recruited in New York City (n = 614) and Philadelphia (n = 540). Eligible participants had to identify as male, be 18 years of age or older, report sex (oral, anal sex, or mutual masturbation) with a man in the past 12 months, and be a resident of the recruitment area. Participation was open to men of any HIV status.
Men were recruited through respondent-driven sampling.12 Individual study sessions were conducted in study offices located in office buildings and community-based organizations. Participants completed an audio computer-assisted self-interview (ACASI). They were asked about HIV testing history, the results of their most recent HIV test, and anal intercourse practices in the prior 3 months with male partners who “told you they were HIV-negative and you had no reason to doubt it,” partners whom “you knew were HIV-positive,” and partners of unknown serostatus.
After they completed the ACASI, participants were tested for HIV using a rapid, oral fluid HIV antibody test (OraQuick Advance). Preliminary positive results were confirmed with Western blot assay. Men who disclosed during eligibility screening that they had previously been diagnosed as HIV-positive underwent Western blot testing only. Men received counseling and referral to services as needed. A full description of the study methods can be found elsewhere.13
All analyses were conducted with unweighted data. Our goal was to describe behavioral patterns but not make population estimates that may be inaccurate. The analytic sample for the serosorting analysis included 724 men (387 Latino MSM and 337 black MSM) who reported on the ACASI that they engaged in anal intercourse in the past 3 months and that their most recent HIV test (outside of this study) was negative. About 72% of the Latino men (277 of 387) and 73% of the black men (245 of 337) received their most recent HIV-negative test result within 12 months of enrollment.
The serosorting results are displayed in Table 1. In the analysis that combined black and Latino MSM, 41.2% always used a condom when they engaged in anal intercourse in the past 3 months. Of those who engaged in UAI, 53.1% did so only with partners reported as being HIV-negative (serosorters) and 46.9% did not limit their UAI to HIV-negative partners. The odds of testing HIV-positive in the study were (1) nonsignificantly higher among serosorters compared with men who always used a condom during anal sex (4.4% vs. 2.7%; odds ratio [OR], 1.68; 95% confidence interval [CI], 0.65–4.32) and (2) significantly higher among men who did not limit UAI to HIV-negative partners compared with serosorters (11.5% vs. 4.4%; OR, 2.81; 95% CI, 1.30–6.05). This latter bivariate association remained significant after controlling for number of UAI partners of any serostatus, age, education, and employment status (OR, 2.54, 95% CI, 1.14–5.68).
Of self-reported HIV-negative MSM who engaged in UAI with male partners, a larger percentage of Latinos (64.1%) than blacks (39.2%) engaged in serosorting. Within each of these 2 groups, the findings on HIV infection paralleled the overall sample, but only one comparison was statistically significant: black MSM who did not limit their UAI to HIV-negative partners had significantly greater odds of testing HIV-positive compared with black MSM who reported that they always used a condom during anal sex in the past 3 months (15.6% vs. 5.4%; OR, 3.25; 95% CI, 1.36–7.77; adjusted for demographic factors: OR, 3.21; 95% CI, 1.32–7.77).
The analysis of strategic positioning was conducted among a subgroup of men who reported that their most recent HIV test was negative and had engaged in UAI with HIV-positive or unknown serostatus male partners in the past 3 months (n = 196). The results are displayed in Table 2. In the analysis that combined black and Latino MSM, 109 of these 196 men (55.6%) engaged in insertive UAI but not receptive UAI with HIV-positive or unknown serostatus partners (strategic positioning). The odds of testing HIV-positive were significantly higher among men who engaged in receptive UAI compared with those who only engaged in insertive UAI with HIV-positive or unknown partners (18.4% vs. 6.4%; OR, 3.28; 95% CI, 1.28–8.39; adjusted for number of UAI partners of any serostatus and demographic factors: OR, 3.24; 95% CI, 1.20–8.69). This association was observed among black MSM (27.8% vs. 7.5%; OR, 4.74; 95% CI, 1.56–14.29; adjusted for number of UAI partners of any serostatus and demographic factors: OR, 4.65; 95% CI, 1.39–15.56) but not among Latino MSM (7.5% vs. 4.8%; unadjusted OR, 1.62; 95% CI, 0.26–10.25).
The findings must be interpreted cautiously because of the small subgroup sample sizes. It is also important to distinguish between harm-reduction at the “group level” and harm-reduction at the “individual level.” The group of self-reported HIV-negative men that serosorted was less likely to test HIV-positive than their counterpart group that did not limit UA to HIV-negative partners. However, serosorting may not reduce risk for every individual within the group. About 4% of the serosorters tested HIV-positive, stemming perhaps from misperception, miscommunication, or wishful thinking about their own or their partner's serostatus. The same issue applies to strategic positioning. It was associated with fewer HIV infections at the group level; however, 6% of the self-reported HIV-negative men who engaged in strategic positioning tested HIV-positive in our study, likely stemming from the risk of infection conferred by engaging in unprotected insertive anal intercourse.5 Consistent with other studies,8,10 the infection rate was lowest among those who always used a condom during anal intercourse.
We do not know whether the serosorting or strategic positioning we observed represents deliberate, on-going harm-reduction strategies or whether these behaviors were limited to the 3-month assessment period. The men were not explicitly asked whether they sought out seroconcordant partners or engaged in insertive rather than receptive anal sex as intentional strategies to reduce risk.
Most of the HIV infections identified in the study probably occurred before the 3-month assessment window. Thus, the fact that the group of serosorters (vs. men who did not limit their UAI to HIV-negative partners) and the group that engaged in strategic positioning (vs. those who did not) were less likely to test HIV-positive in the study suggests that these behaviors may reflect longer-standing behaviors for at least some participants.
In all behavioral groups, we found more new HIV infections among the black than Latino MSM. One explanation is that black MSM are more likely to be exposed to the virus (assuming assortative sexual partnering by race/ethnicity14–17) due to the higher prevalence of HIV infection (including higher rates of unrecognized infection) in the black MSM population than the Latino MSM population.
Methodologically, participants were initially classified as HIV-negative based on questions about HIV testing history and results of their most recent test. Sex partners were classified as HIV-negative only when participants indicated that partners told them they were HIV-negative and participants had no reason to doubt the information. These types of questions may result in fewer misclassifications than overly general questions such as “what is your serostatus?” and “what was the serostatus of your partner(s)?” which may have larger error components. Indeed, the methodological rigor needed for valid conclusions from research studies mirrors the “methodological rigor” needed in real life before serosorting truly reduces risk of HIV infection. If 2 sex partners merely guess at their HIV status, a risky serosorting situation results.6,9 If both partners have recently tested HIV-negative and neither has had unprotected sex with another person, a safer serosorting situation occurs.
In our study, the prevalence of serosorting was higher among self-reported HIV-negative Latino than black MSM, and this difference was statistically significant after controlling for age, education, and employment status. It remains unclear, however, whether proportionally more Latino than black MSM were intentionally engaging in serosorting as a harm-reduction strategy. The difference we observed may reflect the fact that there are more HIV-negative sex partners available in the Latino MSM population than the black MSM population.18
In summary, our findings demonstrate the potentially protective roles of serosorting and strategic positioning at the group level among HIV-negative black and Latino MSM. For any given individual, however, these behaviors may carry risk for infection. Additional research is needed to examine the extent to which men deliberately use these behaviors as harm-reduction strategies and the relative safety they provide.
1. Saurez T, Miller J. Negotiating risks in context: A perspective on unprotected anal intercourse and barebacking among men who have sex with men—where do we go from here? Arch Sex Behav 2001; 30:287–300.
2. Parsons JT, Schrimshaw EW, Wolitski RJ, et al. Sexual harm reduction strategies of HIV-seropositive gay and sexual men: Serosorting, strategic positioning, and withdrawal before ejaculation. AIDS 2005; 19(suppl 1):S13–S25.
3. Eaton LA, Kalichman SC, O'Connell DA, et al. A strategy for selecting sexual partners believed to pose little/no risk for HIV: Serosorting and its implications for HIV transmission. AIDS Care. In press.
4. Van de Ven P, Kippax S, Crawford J, et al. In a minority of gay men, sexual risk practice indicates strategic positioning for perceived risk reduction rather than unbridled sex. AIDS Care 2002; 14:1471–1480.
5. Vittinghoff E, Douglas J, Judson F, et al. Per-contact risk of human immunodeficiency virus transmission between male sexual partners. Am J Epidemiol 1999; 150:306–311.
6. Parsons JT, Severino J, Nanin J, et al. Positive, negative, unknown: Assumptions of HIV status among HIV-positive men who have sex with men. AIDS Educ Prev 2006; 18:139–149.
7. Butler DM, Smith DM. Serosorting can potentially increase HIV transmissions. AIDS 2007; 21:1218–1220.
8. Golden MR, Stekler J, Hughes JP, et al. HIV serosorting in men who have sex with men: Is it safe? J Acquir Immune Defic Syndr 2008; 49:212–218.
9. Zablotska IB, Imrie J, Prestage G, et al. Gay men's current practice of HIV seroconcordant unprotected anal intercourse: Serosorting or seroguessing? AIDS Care 2009; 21:501–510.
10. Jin F, Crawford J, Prestage GP, et al. Unprotected anal intercourse, risk reduction behaviors, and subsequent HIV infection in a cohort of homosexual men. AIDS 2009; 23:243–252.
11. Centers for Disease Control and Prevention. Racial/ethnic disparities in diagnoses of HIV/AIDS—33 states, 2001–2005. MMWR Morb Mortal Wkly Rep 2007; 56:189–193.
12. Heckathorn DD. Respondent-driven sampling II: Deriving valid population estimates from chain-referral samples of hidden populations. Soc Problems 2002; 49:11–34.
13. Marks G, Millett GA, Bingham T, et al. Understanding differences in HIV sexual transmission among Latino and black men who have sex with men: The Brothers y Hermanos study. AIDS and Behav 2009; 13:682–690.
14. Aral SO. Patterns of sexual mixing: Mechanisms for or limits to the spread of STIs? Sex Transm Dis 2000; 76:415–416.
15. Bingham TA, Harawa NT, Johnson DF, et al. The effect of partner characteristics on HIV infection among African Am men who have sex with men in the Young Men's Survey, Los Angeles, 1999–2000. AIDS Educ Prev 2003; 15:39–52.
16. Centers for Disease Control and Prevention. HIV transmission among black college student and nonstudent men who have sex with men–North Carolina, 2003. MMWR Morb Mortal Wkly Rep 2004; 53:731–734.
17. Berry M, Raymond HF, McFarland W. Same race and older partner selection may explain higher HIV prevalence among black men who have sex with men. AIDS 2007; 21:2349–2350.
18. MacKellar DA, Valleroy LA, Secura GM, et al. Unrecognized HIV infection, risk behaviors, and perceptions of risk among young men who have sex with men. J Acquir Immune Defic Syndr 2005; 38:603–614.