Prevalence and Awareness of HIV Infection Among Men Who Have Sex With Men --- 21 Cities, United States, 2008

Men who have sex with men (MSM) are at increased risk for infection with human immunodeficiency virus (HIV). In 2006, 57% of new HIV infections in the United States occurred among MSM (1). To estimate and monitor risk behaviors, CDC's National HIV Behavioral Surveillance system (NHBS) collects data from metropolitan statistical areas (MSAs) using an anonymous cross-sectional interview of men at venues where MSM congregate, such as bars, clubs, and social organizations. This report summarizes NHBS data from 2008, which indicated that, of 8,153 MSM interviewed and tested in the 21 MSAs participating in NHBS that year, HIV prevalence was 19%, with non-Hispanic blacks having the highest prevalence (28%), followed by Hispanics (18%), non-Hispanic whites (16%), and persons who were multiracial or of other race (17%). Of those who were infected, 44% were unaware of their infection. Men who know their current HIV infection status can be linked to appropriate medical care and prevention services. Once linked to prevention services, men can learn ways to avoid transmitting the virus to others. Young MSM (aged 18--29 years) (63%) and minority MSM (other than non-Hispanic white) (54%) were more likely to be unaware of their HIV infection. Efforts to ensure at least annual HIV testing for MSM should be strengthened, and HIV testing and prevention programs should increase their efforts to reach young and minority MSM.

NHBS is a behavioral surveillance system used to monitor prevalence and trends in 1) HIV-related risk behaviors, 2) HIV testing, and 3) use of HIV prevention services among populations at high risk for acquiring HIV, including MSM, injection-drug users, and heterosexuals at increased risk for HIV infection. Data are collected in annual cycles from one risk group per year so that each group is surveyed once every 3 years. The first cycle of NHBS (among MSM) was conducted in 15 MSAs during 2004--2005; behavioral surveys were conducted in 10 MSAs, and HIV testing in conjunction with the behavioral survey was conducted in five MSAs (2). In 2008, NHBS staff members in 21 MSAs collected cross-sectional behavioral risk data and conducted HIV testing among MSM. MSAs were selected based on high prevalence of acquired immunodeficiency syndrome (AIDS); the 21 MSAs included approximately 60% of all prevalent urban U.S. AIDS cases in 2006. MSM were sampled using venue-based, time-space sampling methods. Health department staff members first identified appropriate venues (e.g., bars, clubs, organizations, and street locations) and days and times when men frequented those venues (3). Venues and the corresponding day/time periods (VDTs) were chosen randomly each month. Staff members then systematically approached men at the venues (2). Men eligible for being interviewed were aged ≥18 years, residents of the MSAs, and able to complete the interview in English or Spanish. After participants gave informed consent, trained interviewers administered a standardized, anonymous questionnaire using a handheld computer. The interview consisted of questions about sex, drug use, HIV testing behaviors, and use of HIV prevention services. All respondents were offered anonymous HIV testing, regardless of self-reported HIV infection status, given the opportunity to receive their test results, and anonymously referred to care when appropriate. HIV testing was performed by collecting blood or oral specimens for either Western blot (WB) or immunofluorescence assay (IFA) confirmatory testing in a laboratory or rapid testing at venues using Food and Drug Administration (FDA)--approved tests for use in nonlaboratory settings. A nonreactive rapid test was considered a definitive negative result; reactive (preliminary positive) rapid test results were considered definitive positive only when confirmed by WB or IFA. MSM unaware of their HIV infection were defined as those who tested HIV-positive at the time of the interview but reported that the result of their most recent HIV test was negative, indeterminate, or unknown, or that they had never been tested. Men were compensated both for their time participating in the interview and for taking an HIV test.

In 2008, a total of 28,468 men were approached, and 12,325 were screened for participation in NHBS at 626 venues in 21 MSAs. Of men who were screened, 11,074 (90%) were eligible for the survey. Men were excluded from analysis if they did not consent to and complete both the survey and the HIV test (n = 1,558), did not report sex with a man during the preceding 12 months (n = 1,744), had an indeterminate HIV test result (n = 85), or reported being HIV-positive but had a negative NHBS HIV test result (n = 60). These criteria were not mutually exclusive; a total of 2,921 men were excluded from analysis. Of eligible men, 8,153 (74%) were MSM who met criteria for inclusion in this analysis. The median age of the MSM in this report was 32 years (range: 18--85 years); 44% were non-Hispanic white, 25% Hispanic, 23% non-Hispanic black, 2% Asian, 0.8% Native Hawaiian/Pacific Islander, 0.6% American Indian/Alaska Native, and 4% multiracial or other. Thirty-seven percent had a college education or higher, and 30% reported an annual household income <$20,000. Sixty-seven percent of men reported a household size of one. The majority had health insurance (66%) and had visited a health-care provider during the preceding year (76%) (Table 1).

Among the 8,153 MSM tested, 1,562 (19%) tested positive for HIV (range by MSA: 6%--38%). HIV prevalence was 28% among blacks, 18% among Hispanics, and 16% among whites. HIV prevalence increased with increasing age and decreased with increasing education and income (Table 1).

Of the 1,562 HIV-infected MSM, 680 (44%) were unaware of their infection. The proportion who were unaware of their infection was higher among younger than older MSM (Table 1). The proportion unaware was highest among blacks (59%), lowest among whites (26%), and decreased with increasing education and income. Higher proportions of MSM with no health insurance and those who had not visited a health-care provider during the preceding year were unaware of their infection (Table 1). Fifty-five percent of MSM unaware of their infection had not been tested during the preceding 12 months.

The HIV prevalence by age group and race/ethnicity for MSM aged <30 years was highest among black MSM in each age group. The majority of young black and Hispanic MSM in each age group were unaware of their HIV infection (Table 2).

For comparison with a previous NHBS report of MSM HIV prevalence during 2004--2005, which indicated an HIV prevalence of 26% among MSM and an infection unawareness rate of 48% (4), five MSAs (Baltimore, Maryland; Los Angeles, California; Miami, Florida; New York, New York; and San Francisco, California) were analyzed separately in the analysis of 2008 data. Results indicated that the overall HIV prevalence was 27%, and 48% of HIV-positive participants were unaware of their infection. HIV prevalence among blacks was 40%; 63% were unaware of their infection. These prevalence rates were similar to those from 2004--2005 NHBS data*; the proportion of MSM unaware of their infection did not increase (Table 3).†

Reported by

A Smith, MPH, I Miles, ScD, B Le, MD, T Finlayson, PhD, A Oster, MD, E DiNenno, PhD, Div of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC.

Editorial Note

The findings from this analysis corroborate other surveillance data showing that HIV prevalence among MSM remains high, many HIV-infected MSM are unaware that they are infected with HIV, and minority MSM are disproportionately affected by HIV (5--6). Because MSM represent the only group with increasing HIV incidence and comprise the largest proportion of new infections (1), it is critical to target resources and prevention strategies to MSM. The National HIV/AIDS Strategy§ emphasizes the importance of improving the impact of HIV prevention efforts for MSM. The NHBS data also underscore the specific need for increased HIV testing efforts for all MSM, especially minority MSM; CDC recently broadened its expanded HIV testing initiative to reach more MSM.¶

CDC currently recommends that sexually active MSM get tested for HIV at least once per year (7). NHBS data demonstrate that 55% of MSM who were unaware of their HIV infection had not had an HIV test during the preceding 12 months. This finding suggests that increased efforts to educate MSM and health-care providers about HIV testing guidelines and to reduce barriers to HIV testing for MSM are necessary. Also, because 45% of MSM who were unaware of their infection were tested within the previous 12 months, shorter intervals for testing some MSM might be warranted and should be considered in future recommendations.

This analysis shows racial and economic disparities in both HIV prevalence and awareness of HIV infection. Racial disparities were observed in the youngest age group (18--19 years) and increased with age. CDC is working to decrease these racial disparities and currently funds HIV prevention programs for young, minority MSM.** The economic disparities described in this report are consistent with those reported among heterosexuals participating in NHBS.†† This reinforces the need for targeting prevention efforts to low-income populations, which might reduce HIV infection rates among MSM.

The findings in this report are subject to at least four limitations. First, because the survey was administered by an interviewer, positive HIV status might have been underreported during the interview, given the sensitive nature of the topic, thereby inflating estimates of MSM unaware of their infections. Second, 135 MSM who reported being HIV-positive but who had a negative or indeterminate HIV test result were excluded from analysis because of the possibility that they had false-negative NHBS test results; however, including these men as HIV-positive would have yielded a similar overall HIV prevalence (20% compared with 19%). Third, comparisons of the NHBS-MSM datasets collected during 2004--2005 and 2008 should be made cautiously, because this analysis did not control for demographic differences in the samples, which might have influenced the percentages reported. Finally, these findings are limited to men who frequented MSM-identified venues (most of which were bars [45%] and dance clubs [22%]) during the survey period in 21 MSAs with high AIDS prevalence; the results are not representative of all MSM. A lower HIV prevalence (11.8%) has been reported among MSM in the general U.S. population (8).

The high proportion of MSM unaware of their HIV infection continues to be a serious public health concern, because these MSM account for the majority of estimated new HIV transmissions in the United States (9). Persons aware of their HIV infection often take substantial steps to reduce their risk behaviors, which could reduce HIV transmission (10). Whereas many MSM described in this report had not received an HIV test during the preceding 12 months, 45% of MSM who were unaware of their infection did report having an HIV test during the preceding 12 months, indicating they had acquired HIV recently or reported an incorrect HIV test result to the interviewer.

NHBS provides important information to guide and monitor HIV prevention efforts nationally and locally and will be critical for monitoring the impact of the National HIV/AIDS Strategy. The 2008 NHBS data show that MSM remain a key target of strategies to reduce HIV incidence and decrease racial and socioeconomic disparities in the United States.

Acknowledgments

This report is based, in part, on contributions by National HIV Behavioral Surveillance system staff members, including J Taussig, R Gern, T Hoyte, L Salazar, B Hadsock, Atlanta, Georgia; C Flynn, F Sifakis, Baltimore, Maryland; D Isenberg, M Driscoll, E Hurwitz, Boston, Massachusetts; N Prachand, N Benbow, Chicago, Illinois; S Melville, R Yeager, A Sayegh, J Dyer, A Novoa, Dallas, Texas; M Thrun, A Al-Tayyib, R Wilmoth, Denver, Colorado; E Higgins, V Griffin, E Mokotoff, Detroit, Michigan; M Wolverton, J Risser, H Rehman, Houston, Texas; T Bingham, E Sey, Los Angeles, California; M LaLota, L Metsch, D Beck, D Forrest, G Cardenas, Miami, Florida; C Nemeth, C-A Watson, Nassau-Suffolk, New York; WT Robinson, D Gruber, New Orleans, Louisiana; C Murrill, A Neaigus, S Jenness, H Hagan, T Wendel, New York, New York; H Cross, B Bolden, S D'Errico, Newark, New Jersey; K Brady, A Kirkland, Philadelphia, Pennsylvania; V Miguelino, A Velasco, San Diego, California; H Raymond, W McFarland, San Francisco, California; SM De León, Y Rolón-Colón, San Juan, Puerto Rico; M Courogen, H Thiede, N Snyder, R Burt, Seattle, Washington; M Herbert, Y Friedberg, D Wrigley, J Fisher, St. Louis, Missouri; and P Cunningham, M Sansone, T West-Ojo, M Magnus, I Kuo, District of Columbia.

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