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CDC: HIV Rate in Young US MSM Twice Higher Than in Sub-Saharan Africa
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19th Conference on Retroviruses and Opportunistic Infections, March 5-8, 2012, Seattle
Mark Mascolini
HIV prevalence stood at 10.5% among 1889 young men who have sex with men (MSM) studied by the CDC in 21 US cities [1]--a rate twice higher than that among adults across sub-Saharan Africa. Annual HIV incidence among these MSM measured 2.9%. HIV prevalence and incidence were higher in blacks (16.5% and 5.1%) than in other racial/ethnic groups. Among 198 men who tested positive during the study, 136 (69%) did not already know they had HIV infection.
The CDC's most recent national HIV incidence study determined that overall incidence (the new infection rate) remained flat at around 48,000 yearly among people 13 years old and older from 2006 through 2009 [2]. But incidence rose 34% in those years among young MSM and 48% among young black/African American MSM.
In 2008 a CDC team used venue-based sampling to recruit young MSM in 21 cities across the country. Study participants had to be at least 18, a resident of the urban area, and able to complete a survey in English or Spanish. The analysis focused on men from 18 to 24 who had at least 1 male sex partner in the last 12 months. All study participants completed the survey and got tested for HIV.
Eighteen-to-19-year-olds made up 22.4% of the study group, 20-to-22-year-olds 43.6%, and 23-to-24-year-olds 34.0%. Blacks made up the largest proportion of respondents (35.9%), followed by Hispanics (29.2%), and whites (26.2%). Only 10% of these MSM had less than a high school education, while 53.5% had at least some college. Almost half of respondents, 47.6%, were in the lowest of three income brackets considered, 0 to $19,999 yearly.
One third of these men were 16 or younger when they had their first anal sex with another man. Three quarters visited their healthcare provider in the past 12 months, and two thirds had an HIV test in the past year. While 1691 men (89.5%) had a negative HIV test, 7.2% had a positive test for the first time, and 3.3% had a positive test after a previous positive test. Among the 198 men with a positive test during the study, 136 (69%) did not know they had HIV infection.
Overall HIV prevalence measured 10.5%--twice the estimated HIV prevalence among 15-to-49-year-olds in sub-Saharan Africa in 2009 [3]. Prevalence stood at 16.5% among young black MSM (almost as high as South Africa's 17.8% adult rate), at 6.9% among Hispanic MSM, and at 6.2% among white MSM. CDC statisticians calculated an overall HIV incidence of 2.9% yearly, highest in blacks at 5.1% yearly, followed by Hispanics at 1.9% and whites at 1.6%.
Most young men surveyed (69.3%) said they had a main partner who was at least 5 years older. While 2.6% of main partners were HIV-positive, 73.8% were negative, and 23.5% had an unknown HIV status. Relationships with main partners did not last long: 46% were over within 6 months. At the time of the survey, 71.8% of men did not have a main partner. While 43.9% of respondents had unprotected anal intercourse with a main partner, 23.4% did so with a casual partner.
Several factors raised the risk of being HIV-positive but unaware of being infected, at the following adjusted prevalence ratios (APR) (and 95% confidence intervals):
-- Black race (compared with white): APR 2.9 (1.8 to 4.7)
-- Less than high school (compared with some college): APR 1.8 (1.04 to 2.9)
-- Alcohol/drugs before/during last sex: APR 1.9 (1.01 to 3.5)
-- Visited provider in last year: APR 1.9 (1.3 to 2.9)
-- Most recent HIV test more than a year ago: APR 1.5 (1.2 to 2.0)
Men who were 18 or 19 were 60% less likely to be HIV-positive and unaware than men who were 23 or 24 (APR 0.40, 95% CI 0.2 to 0.7).
The CDC team stressed that "the short duration of main partnerships and the higher occurrence of unprotected anal intercourse with main partners could substantially increase HIV risk" among young MSM in the United States.
To slow the spread of HIV among MSM, the investigators urged health professionals to use the CDC's High-Impact Prevention approach with MSM, which combines "targeted, scientifically proven interventions that are cost effective and scalable." See http://www.cdc.gov/hiv/strategy/dhap/pdf/nhas_booklet.pdf.
References
1. Balaji A, Bowles K, Le B, Paz-Bailey G, Oster A. High HIV incidence and prevalence and associated factors among young MSM in 21 cities: US, 2008. 19th Conference on Retroviruses and Opportunistic Infections. March 5-8, 2012. Seattle. Abstract 1096.
2. Prejean J, Song R, Hernandez A, et al; HIV Incidence Surveillance Group. Estimated HIV incidence in the United States, 2006-2009. PLoS One. 2011;6(8):e17502. http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017502.
3. UNAIDS. UNAIDS report on the global AIDS epidemic 2010.
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