Background:  The use of the Internet to meet sex partners makes this media a potential target for education and intervention in preventing risky sex behavior associated with HIV/AIDS. To assess this potential, we compared the frequency of unprotected anal intercourse (UAI) with partners met on line vs off-line and associated risks among men who have sex with men (MSM)

Methods:  From October 2003 to April 2004, men were recruited online. A banner linking to the survey was posted on 14 different gay-oriented Web sites whose content varied from sexually explicit to general information. Over 4000 men completed the survey. Analysis includes 1707 men from the United States or Canada who had sex in the 3 months before the survey with a non-main male partner. Behavior in the last sexual encounter was analyzed.

Results:  Median age of the respondents was 36 (range 18 to 85); 49% had college degrees; most self-identified as gay (76%); 51% met their last sex partner on-line; 10.6% of men tested reported being HIV⁺; and 4.4% reported crystal meth use before sex. Prevalence of, and risk factors for, UAI were analyzed separately for men reporting multiple-partner (n = 381) and single-partner (n = 1326) encounters. Of those reporting anal sex, 111/230 (48%) with multiple-partner and 367/641 (57%) with single-partner encounters reported UAI. Among HIV⁺ men with single-partners, only 11/36 (30%) reporting UAI had a known HIV⁺ partner. In bivariate analysis of multiple- and single- partner groups, the proportions reporting UAI were similar for partners met on-line and off-line. In multivariate analysis of men with multiple-partners, UAI was significantly associated with meeting partners off-line (odds ratio [OR] 2.0, p = 0.048) and being HIV⁺ (OR 2.97, p = 0.017) in a model that included age and education, as well as use of crystal meth, Viagra, and alcohol before sex. The same model, plus a partner HIV concordance variable, was used to examine risk of UAI in men reporting single-partner sex. Crystal meth (OR 5.8, p = 0.001), no college degree (OR 1.7, p=.002) and HIV⁺ concordance (OR 3.6, p = 0.036) were associated with UAI. No difference in risk for UAI was found for partners met on-line versus off-line.

Conclusion:  More than 25% of men recruited online in this study had UAI with 1 or more partners in their last encounter. The large number of men on-line and the diversity of their risk and ways of meeting partners show that the Internet provides a unique opportunity for far-reaching behavioral interventions, particularly those that incorporate information about links between UAI and drug use.

Keywords: Men Who Have Sex with Men; HIV Transmission Risks; Internet and Sexual Behavior