Crystal Methamphetamine Use Predicts Incident STD Infection Among Men Who Have Sex With Men Recruited Online: A Nested Case-Control Study

BACKGROUND: Among men who have sex with men (MSM), the number of newly diagnosed human immunodeficiency virus (HIV) infections has increased by approximately 60% since 1999. Factors that may be contributing to this resurgence include a widely reported increase in bacterial sexually transmitted diseases (STDs) among HIV-positive and HIV-negative MSM, as well as unsafe sexual practices. OBJECTIVE: This research was undertaken to learn more about risk behaviors associated with an incident STD among MSM. METHODS: A nested case-control study was conducted, using data from a cross-sectional Internet survey of MSM (N=2643), which investigated risk behaviors during a 6-month period in 2001. Chi-square and logistic regression methods were used to estimate the likelihood of acquiring an incident STD versus no STD. RESULTS: Eighty-five percent of the respondents were white, 46% were under age 30, and 80% had met sex partners online; 7% were HIV-positive. Men with an incident STD were more likely than men without an STD to report drug use (crystal methamphetamine odds ratio 3.8; 95% confidence interval 2.1-6.7; cocaine OR 2.3; 95% CI 1.2-4.2; ecstasy OR 2.2; 95% CI 1.3-3.8; Viagra OR 2.1; 95% CI 1.2-3.7), alcohol before or during sex (OR 1.9; 95% CI 1.2-2.9), and high-risk sexual behavior (unprotected anal intercourse OR 5.0; 95% CI 2.8-8.9; multiple sex partners OR 5.9; 95% CI 2.5-13.8). In the multivariate analysis, significant independent predictors associated with an incident STD were crystal methamphetamine use (adjusted OR 2.0; 95% CI 1.1-3.8), unprotected anal intercourse (adjusted OR 3.4; 95% CI 1.9-6.3), and 6 or more sex partners during the study period (adjusted OR 3.3; 95% CI 1.4-7.8). CONCLUSION: Identifying and treating MSM who have STDs, or who are at increased risk for acquiring STDs, is crucial in preventing the further spread of disease. In addition, there is a need to integrate HIV/STD and substance use prevention and education into Web-based and community-based venues.