Actor-Partner Effects of Male Couples Substance Use with Sex and Engagement in Condomless Anal Sex.

Few studies have examined actor-partner effects about male couples' substance use with sex. Dyadic data from 361 male couples were used to examine these effects regarding engagement in condomless anal sex (CAS) by type of partner and substance. Couples with one or both partners reported using marijuana, amyl nitrates, party drugs, and/or stimulants with sex in their relationship was positively associated with them having had CAS. Actor-partner effects for stimulant use with sex with the main partner were associated with CAS with a casual MSM partner. Only an actor effect for stimulant use with sex with a casual MSM partner was associated with CAS with that partner type, and an actor effect for marijuana use with sex for both partner types was associated with CAS with both partner types. These findings illuminate the need for further inquiry about male couples' substance use with sex for HIV prevention.