Age and Age Discordance Associations with Condomless Sex Among Men Who Have Sex with Men.

We explored the effect of older partner's age and age difference between partners on condomless sex among men who have sex with men (MSM). We analyzed dyads (n = 1720) from participants (n = 969) in the Sexual Acquisition Transmission of HIV Cooperative Agreement Program. We used modified Poisson regression to model the probability of a sexual encounter's being condomless as a function of older partner's age and age difference between partners adjusting for HIV status, substance use, race/ethnicity, and partner type. We found an interaction between older partner's age and age difference (p < 0.05). Condomless sex decreased with increasing age of the older partner when the age difference was 5-9 years (p = 0.004) or ≥10 years (p = 0.04), but not when <5 years. Condomless sex was less likely among older MSM when there was ≥5 years age difference between partners than <5 years difference. Both age and age discordance affect the likelihood of a sexual encounter between MSM being condomless.