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The burden of human immunodeficiency virus (HIV) is high among gay, bisexual, and other men who have sex with men (MSM).1 High HIV prevalence, lack of awareness of HIV-positive status, unprotected anal sex, and increased viral load among HIV-positive MSM not on antiretroviral treatment contribute substantially to new infections among this population. CDC analyzed data from the National HIV Surveillance System (NHSS) to estimate the percentage of HIV diagnoses among MSM by area of residence and data from the National HIV Behavioral Surveillance System (NHBS) to estimate unprotected anal sex in the past 12 months among MSM in 2005, 2008, and 2011; unprotected discordant anal sex at last sex (i.e., with a partner of opposite or unknown HIV status) in 2008 and 2011; and HIV testing history and the percentage HIV-positive but unaware of their HIV status by the time since their last HIV test in 2011. This report describes the results of these analyses. In all but two states, the majority of new HIV diagnoses were among MSM in 2011. Unprotected anal sex at least once in the past 12 months increased from 48% in 2005 to 57% in 2011 (p<0.001). The percentage engaging in unprotected discordant anal sex was 13% in 2008 and 2011. In 2011, 33% of HIV-positive but unaware MSM reported unprotected discordant anal sex. Among MSM with negative or unknown HIV status, 67% had an HIV test in the past 12 months. Among those tested recently, the percentage HIV-positive but unaware of their infection was 4%, 5%, and 7% among those tested in the past ≤3, 4-6, and 7-12 months, respectively. Expanded efforts are needed to reduce HIV risk behaviors and to promote at least annual HIV testing among MSM.
Data reported through June 2012 to NHSS were used to estimate* HIV diagnoses among MSM by area of residence in 2011. Data from NHBS† were used to describe adjusted trends in unprotected anal sex§ in the past 12 months among MSM in 2005, 2008, and 2011.¶ Data from 2008 and 2011 were used to calculate the prevalence of unprotected discordant anal sex** at last sex. Chi-square tests†† were used to evaluate differences between 2008 and 2011 by HIV status, race/ethnicity, and age. Data from 2011 were used to evaluate the difference in the percentage engaging in unprotected discordant anal sex at last sex among HIV-positive aware,§§ HIV-positive unaware, and HIV-negative MSM. Adjusted¶¶ prevalence ratios (APRs) and 95% confidence intervals (CIs) are presented. Data from 2011 were used to assess HIV testing history after excluding self-reported HIV-positive MSM, and the percentage HIV-positive but unaware, by time since the last HIV test.
In 2011, MSM accounted for at least half of persons diagnosed with HIV in all but two states (Figure 1). The percentage of MSM reporting unprotected anal sex at least once in the past 12 months increased from 2005 to 2011, from 48% in 2005, to 54% in 2008, and 57% in 2011 (p<0.001). The trend was statistically significant among self-reported HIV-negative or unknown status MSM (47%, 54%, and 57%, respectively; p<0.001), but not statistically significant for self-reported HIV-positive MSM (55%, 57%, and 62%, respectively; p=0.054) (Table 1).
The percentage of MSM engaging in unprotected discordant anal sex at last sex was 13% in both 2008 and 2011 (Table 2). In 2011, 33% of HIV-positive but unaware MSM had unprotected discordant anal sex at last sex. This percentage was more than twice as high as the percentage among those who were HIV-positive aware (13%) (APR = 2.2; CI = 1.7-2.9; p<0.001) or HIV-negative (12%) (APR = 2.8; CI = 2.2-3.5; p<0.001).
Among HIV-negative or unknown status MSM, 67% reported testing for HIV in the past 12 months. A higher percentage tested in the past 3 months (31%) than in the past 4-6 months (17%) or in the past 7-12 months (19%) (Figure 2). The percentage HIV-positive but unaware was 5% among those who tested in the past 12 months: 4%, 5%, and 7% among those tested ≤3, 4-6, and 7-12 months ago, respectively (Figure 3).
Reported by: Gabriela Paz-Bailey, M.D., Ph.D., H. Irene Hall, Ph.D., Richard J. Wolitski, Ph.D., Joseph Prejean, Ph.D., Michelle M. Van Handel, M.P.H., Binh Le, M.D., Michael LaFlam, Linda J. Koenig, Ph.D., Maria Corazon Bueno Mendoza, Ph.D., Charles Rose, Ph.D., Linda A. Valleroy, Ph.D., Div of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC. Corresponding contributor: Gabriela Paz-Bailey, firstname.lastname@example.org, 404-639-4451.
Although MSM are a small proportion of the population, they represent the majority of persons diagnosed with HIV in nearly every U.S. state. Unprotected anal sex in the last 12 months increased nearly 20% among MSM from 2005 to 2011. MSM unaware of their HIV-positive status were more than twice as likely to have unprotected discordant anal sex at last sex as MSM who were either HIV-negative or HIV-positive aware. Only 67% of MSM had tested for HIV in the past 12 months.
Unprotected anal sex is a high-risk practice for HIV infection, with receptive anal sex having the highest risk.2 Unprotected anal sex also places MSM at risk for other sexually transmitted infections such as syphilis, chlamydia, and gonorrhea. Although condoms can reduce the risk for HIV transmission, they do not eliminate risk and often are not used consistently.3 Some MSM attempt to decrease their HIV risk by engaging in unprotected sex only with partners perceived to have the same HIV status as their own. However, this practice is risky, especially for HIV-negative MSM, because MSM with HIV might not know or disclose that they are infected and men's assumptions about the HIV status of their partners can be wrong.2
The reasons for the increase in unprotected anal sex are not fully known but might partially reflect the adoption of presumed risk-reduction strategies, such as engaging in unprotected sex only with partners perceived to have the same HIV status as one's own.4 The fact that the same percentage of MSM engaged in unprotected discordant anal sex at last sex in 2008 and 2011 supports this hypothesis.
Among MSM participating in the National HIV Behavioral Surveillance System (NHBS) in 2011, 18% were HIV-positive.5 Awareness of HIV-positive status among HIV-infected MSM increased from 56% in 2008 to 66% in 2011 in the 20 cities participating in NHBS.5 However, one third of HIV-positive MSM in NHBS did not know that they were infected with HIV,5 and a high percentage of them reported recent unprotected discordant anal sex with a partner of HIV-negative or unknown status. CDC found that MSM who were HIV-positive but unaware were more than two times more likely to engage in unprotected discordant anal sex, compared with HIV-positive aware or HIV-negative MSM. Persons aware of their infection are less likely to transmit the virus,6 and HIV testing is an essential first step in the care and treatment of those who are HIV-positive. HIV treatment can lower viral load, improving health outcomes and reducing the likelihood of HIV transmission. About eight transmissions would be averted for every 100 persons newly aware of their infection as a result of HIV treatment and reductions in risk behavior.6 CDC recommends that persons at high-risk for HIV, such as sexually active MSM, be tested at least annually.7,8 However, in this analysis one third of MSM had not tested for HIV in the past 12 months. Increased use of HIV testing and more frequent testing among sexually active MSM might reduce the number of men unaware of their HIV status and reduce HIV transmission.
The findings in this report are subject to at least two limitations. First, NHBS data are from MSM who were recruited at venues in large cities. Thus, results might not be generalizable to all MSM. Second, except for HIV testing results, analyses were based on self-reported data and might be subject to social desirability and recall bias.
Sexually active MSM should be tested at least annually for HIV and other sexually transmitted infections. Sexually active MSM can take steps to make sex safer such as choosing less risky behaviors, using condoms consistently and correctly if they have vaginal or anal sex, reducing the number of sex partners, and if HIV-positive, letting potential sex partners know their status.2 For some MSM at high risk, taking preexposure or postexposure prophylaxis can reduce risk.9 Health-care providers and public health officials should work to ensure that 1) sexually active, HIV-negative men are tested for HIV at least annually (providers may recommend more frequent testing, for example every 3-6 months); 2) HIV-negative MSM who engage in unprotected sex receive risk-reduction interventions; and 3) HIV-positive MSM receive HIV care, treatment, and prevention services. Reducing the burden of HIV among MSM is fundamental to reducing HIV infection in this country.
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