Adjusted relative hazards of HIV seroconversion (without accounting for condoms) among North American men who have sex with men from four longitudinal cohort studies, 1995–2007.

*seroconversion.**adjusted for age, race, number of sexual partners, any methamphetamine and popper use in the last six months, and intervention assignment.## models 1 and 2 are equivalent apart from using different groups as the reference category.