UCLA

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.