Objective: The objective of this study was to measure associations of unprotected anal intercourse (UAI) and substance use by sexual partner (regular vs. casual) and role [insertive (I) vs. receptive (R)].
Goal: The goal of this study was to identify determinants of the association of specific drugs and UAI.
Study: We conducted a prospective study of young men who have sex with men (MSM), 1997–2002. Odds ratios (ORs) for association of substance use and UAI during the previous year were adjusted for age and calendar year.
Results: UAI was significantly associated with sexual situation-specific use of marijuana (OR, 1.43), crystal methamphetamine (OR, 1.75), ecstasy (OR, 1.88), and ketamine (OR, 2.17); global use associations were similar. Situation-specific associations with alcohol (OR, 1.93) and γ-hydroxybutyrate (GHB; OR, 1.98) were not seen with global measures. GHB and ketamine were specifically associated with IUAI with regular partners, and methamphetamine with RUAI with casual partners.
Conclusion: Type of drug use measure, partner, and role are important determinants of the association of specific substances and UAI.