Paper # 971   
A Comparison of Sexual Behavior Patterns among Heterosexual Men and Women and Men Who Have Sex with Men
Sara Nelson*1, M Morris1, B Foxman2, S Aral3, L Manhart1, K Holmes1, and M Golden1
1Univ of Washington, Seattle, US; 2Univ of Michigan, Ann Arbor, US; and 3CDC, Atlanta, GA, US

"Background: Men who have sex with men (MSM) have higher rates of HIV and many other sexually transmitted infections (STI) than heterosexual men and women. This elevated risk reflects biological and behavioral factors.

Methods: We compared sexual behavior patterns between MSM and heterosexuals using 4 population-based random digit dialing (RDD) surveys. A 1996 to 1998 survey of MSM in 4 US cities and 2 surveys of Seattle MSM (2003, 2006) provided estimates for MSM; a 2003 to 2004 Seattle survey provided data about heterosexual men and women.

Results: The heterosexual survey targeted a younger population (age 18 to 39 years vs age ≥18 years), but participants were similar to MSM in education and race/ethnicity. Age at same-sex sexual debut was slightly younger (age 16.5 to 17.0 years) than opposite-sex sexual debut (17.6), although among MSM anal sex sexual debut was years later (19.6 to 20.2). Among those aged 18 to 24 years, the median lifetime number of sex partners was 4 in heterosexuals and 15 in MSM. The proportion of heterosexuals who formed a new partnership in the prior year declined from 44% at age 18 to 24 years to 15% at age 35 to 39 years. In contrast, among MSM, 86% of 18 to 24 year olds and 72% of MSM aged 35 to 39 years formed a new partnership in the prior year. The median lifetime number of sex partners for persons aged 35 to 39 years was 10 among heterosexuals and 67 among MSM. Over one-third of MSM aged <30 years had a recent partner who was >5 years older, compared to only 7% of male and 20% of female heterosexuals. MSM reported that 51% of their recent partnerships, and 42% of their recent anal sex partnerships, had lasted ≤3 months, compared to only 22% of heterosexual men and 10% of women. Among recent partnerships lasting ≤3 months, approximately two-thirds of MSM always used condoms during insertive anal sex and three-quarters during receptive anal sex; only 53% of heterosexuals in partnerships of similar duration reported consistent condom use. For longer partnerships, consistent condom use ranged from 25 to 50% in MSM and was 23% in heterosexuals. In the Seattle surveys, MSM met 17% of their most recent partners online compared with only 3% of heterosexuals.

Conclusions: MSM have higher early rates of partnership acquisition, continue to form partnerships later into life, meet more partners online, and display more age disassortative mixing than heterosexuals. These factors likely help explain the higher HIV and STI rates among MSM, despite higher levels of condom use."
These are median numbers and do not represent the highest or lowest reports