Dose-response associations between number and frequency of substance use and high-risk sexual behaviors among HIV-negative substance-using men who have sex with men (SUMSM) in San Francisco

Abstract

We evaluated the relationship between frequency and number of substances used and HIV risk [ie, serodiscordant unprotected anal intercourse (SDUAI)] among 3173 HIV-negative substance-using MSM. Compared with nonusers, the adjusted odds ratio (AOR) for SDUAI among episodic and at least weekly users, respectively, was 3.31 [95% confidence interval (CI), 2.55 to 4.28] and 5.46 (95% CI, 3.80 to 7.84) for methamphetamine, 1.86 (95% CI, 1.51 to 2.29) and 3.13 (95% CI, 2.12 to 4.63) for cocaine, and 2.08 (95% CI, 1.68 to 2.56) and 2.54 (95% CI, 1.85 to 3.48) for poppers. Heavy alcohol drinkers reported more SDUAI than moderate drinkers [AOR, 1.90 (95% CI, 1.43 to 2.51)]. Compared with nonusers, AORs for using 1, 2, and ≥3 substances were 16.81 (95% CI, 12.25 to 23.08), 27.31 (95% CI, 18.93 to 39.39), and 46.38 (95% CI, 30.65 to 70.19), respectively. High-risk sexual behaviors were strongly associated with frequency and number of substances used.

Figures

FIGURE 1

Multivariable logistic regression of SDUAI and substance use patterns among HIV-negative SUMSM surveyed, San Francisco, CA, 2009–2012. A, Substance use frequency and SDUAI. 95% CIs are Bonferonni adjusted. Referent group = substance users who did not report using (top to bottom) methamphetamine, cocaine, poppers, or alcohol, respectively. Episodic use = less than weekly use. Moderate alcohol use = less than 4 drinks per day; heavy alcohol use = 4 or more drinks per day. Models adjusted for age and race/ethnicity. [Compared with episodic users, the AOR for SDUAI among at least weekly users of methamphetamine, cocaine, and poppers was 1.65 (Bonferroni-adjusted 95% CI, 1.09 to 2.49) 1.68 (95% CI, 1.12 to 2.54), and 1.22 (95% CI, 0.88 to 1.70), respectively. Compared with moderate alcohol users, the AOR for SDUAI among heavy alcohol users was 1.90 (95% CI, 1.43 to 2.51)]. Panel B: Number of substances used before or during UAI and SDUAI. 95% CIs are Bonferonni adjusted. Referent group = substance users who reported not using any substances before or during UAI. Number of substances = any combinations of the following substances: methamphetamine, cocaine, alcohol, poppers, crack, ecstasy, and heroin (sensitivity analyses that included marijuana and erectile dysfunction drug use resulted in similar trends showing an increase in risk associated with greater number of substances used). Model adjusted for age and race/ethnicity. [SDUAI AOR among those who use 2 vs. 1 and 3 or more vs. 2 substances before or during UAI were 1.62 (95% CI, 1.15 to 2.29) and 1.70 (95% CI, 1.10 to 2.63), respectively].