The effects of intimate relationship characteristics on unprotected anal intercourse among same-sex male couples in China: a dyadic analysis using the actor-partner interdependence model.

Background: Unprotected anal intercourse (UAI) within the context of concurrent sexual relationship are prevalent among men who have sex with men (MSM) who have regular male sex partners and it aggravates the risk of HIV infection among this community. The aim of this study was to assess the effect of intimate relationship characteristics on UAI among MSM couples at the dyadic level.
Methods: Two hundred four MSM couples were recruited from a HIV testing clinic from April 2017 to April 2018 in Guangzhou, China. The actor-partner interdependence model (APIM) was applied for dyadic analysis. Each MSM couple was divided into the insertive role and the receptive role according to their regular anal sex role. In this context, actor effect is the impact of an MSM's intimate relationship characteristics on his own UAI, and partner effect is the impact of his partner's intimate relationship characteristics on his UAI.
Results: Of the 408 participants, 58.82% had UAI with regular male sex partner (UAI-RP) and 8.09% had concurrent UAI. Intimate relationship characteristics were associated with concurrent UAI, but not associated with UAI-RP. For the receptive role, his relationship investment exerted significant actor and partner effects on concurrent UAI (AOR _actor  = 1.31, P < 0.001; AOR _partner  = 1.17, P < 0.001). Meanwhile, receptive role's violence experience within relationship exerted significant actor effects on his own concurrent UAI (AOR _actor  = 6.43, P = 0.044).
Conclusions: Relationship investment and violence experience influenced concurrent UAI among MSM couples and it varied in different sex roles. Additional assistance on empowerment, relationship therapy and sexual agreement is urgently needed to reduce their high possibility on engagement of HIV-related risk behaviors.