Men who have sex with men (MSM) continue to represent the majority of all new HIV diagnoses in the United States (US); developing and testing interventions to serve MSM is a high priority for HIV prevention [1,2]. Couples Voluntary Counseling and Testing (CVCT) is an African testing service that has been recently adapted for use with US male couples who have also expressed high levels of hypothetical willingness to participate in CVCT [3,4]. The African CVCT intervention includes an educational component to help couples understand that HIV serodiscordance is possible – that is, that one partner may be HIV-positive while the other is HIV-negative. It is not clear whether MSM in the US would also benefit from education about the possibility of HIV serodiscordance in the adapted CVCT intervention for MSM. Limited available data suggest that MSM tend to assume HIV partner concordance [5,6]; MSM are more likely to engage in unprotected anal intercourse (UAI) with partners who are perceived to share the same HIV serostatus, compared to those who are HIV discordant or whose status they do not know [7,8].

Data were from the 3-month follow-up time point of an online HIV prevention research study for US MSM. Methods have been previously reported [9]. Briefly, MSM were recruited online from MySpace.com from March-April, 2009 in the US. Men who were white, black, or Hispanic and who consented to prospective follow-up were invited to participate in a 3-month follow-up survey July-August, 2009.

In addition to demographic and behavioral information, the survey collected data on men’s understanding of the possibility of HIV serodiscordance, measured using responses to the statement: “in a couple that has been having sex for several years, if one partner is HIV-negative the other partner is also HIV-negative.” Men who responded “false” were considered to understand that serodiscordance is possible; others were considered not to understand. Using logistic regression in SAS 9.3 (Cary, NC), we calculated crude odds ratios and 95% confidence intervals (CI) for the associations of understanding that serodiscordance is possible with selected demographic characteristics and sexual risk behaviors. Two-tailed Wald tests and an alpha level of 0.05 were used for significance testing.

From 428 total survey respondents, we excluded one man with missing data and one man responding “prefer not to answer” to the serodiscordance question. Most respondents were between 18-24 years of age, and over 75% had a main male sex partner in the last 12 months (Table 1). Over 70% of respondents reported UAI in the last 12 months. nearly half had received and HIV test in the last 12 months and about a quarter had never been tested for HIV. Over 30% did not know their most recent male sex partner’s HIV status.

Of 426 men included in the analysis, 21.1% (90) of MSM were not aware that serodiscordance is possible: 11.5 percent (49) responded “true” and 9.6% (41) responded “I don’t know” to the question about serodiscordance. The odds of not understanding that serodiscordance is possible were 2.0 (CI: 1.1, 3.8) times as high for men who had never tested for HIV, compared to the odds for men who had tested for HIV 0-6 months previously. Additionally, the odds of not understanding that serodiscordance is possible were 2.2 (CI: 1.1-4.5) times as high among men with a high school education or less, compared to the odds for men who had completed at least some college.

A substantial proportion of young, internet-using MSM in the United States may not understand that HIV serodiscordance is possible within sexual partnerships. Lack of understanding may occur especially among men not previously tested for HIV and those with less educational attainment. These same factors have been recently reported to be associated with lower levels of general HIV knowledge [10].

We recognize several important limitations to our work. First, we were limited to a single item for this assessment, and the measure is imperfect. We considered respondents who answered “I don’t know” to not be aware of the possibility of serodiscordance. However, even if we only considered those who endorsed the item as true as not being aware of the possibility of serodiscordance, our primary conclusion - that an important proportion of young MSM are not definitively certain that serodiscordance is possible - is still valid. We also acknowledge that our sample is not representative of all US MSM, or all internet-using MSM.

Based on these results, we recommend that CVCT provided to male couples in the United States should include education on HIV serodiscordance. Since approximately one in six MSM who had been previously tested for HIV also did not recognize the possibility of serodiscordance, this concept might also be important to include in general HIV/AIDS educational interventions and standard prevention counseling with individuals receiving HIV counseling and testing.

The authors confirm that this article content has no conflict of interest.