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 gamma-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.