Socializing patterns and their associations with unprotected anal intercourse (UAI), HIV, and syphilis among men who have sex with men (MSM) and transgender women (TW) in Peru

Background: Sexual behavior is tied to social behavior, yet the associations between socializing patterns and UAI, HIV and STI prevalences remain underexplored in MSM and TW from developing countries. Methods: We analyzed HIV sentinel surveillance data from MSM/TW in Lima, Peru (2011). We assessed the correlates of the following outcomes: 1) UAI within the past three months, 2) HIV, and 3) syphilis (RPR ≥ 1:16); with the following exposure variables within the past six months: 1) MSM/TW venue attendance, and 2) social network size (number of MSM/TW contacts). All models were stratified by sexual identity and adjusted for age, education, and income. Results: Of 2,760 participants, 42.4% self-identified as homosexual, 32.3% bisexual, 8.9% heterosexual, and 16.4% transgender. UAI was reported by 85.8%, and HIV and syphilis diagnosed in 12.0% and 7.0%, respectively. MSM/TW venue attendance was lowest among heterosexual (68.6%) and highest among homosexual (86.0%) respondents. MSM/TW network size was smallest among heterosexual (median 3; IQR: 1-5) and largest among transgender (6; 2-15) respondents. Among heterosexual participants, those who attended MSM/TW venues were more likely to report UAI than those who did not (AOR: 3.41, p =.01). Each additional MSM/TW social network member was associated with increased odds of HIV in bisexual respondents (AOR: 1.01, p =.02) and syphilis in homosexual respondents (AOR: 1.00, p =.04). Conclusions: UAI, HIV, and syphilis were associated with MSM/TW venue attendance and social network size differently according to sexual identity in Peru, warranting further investigation for implementing social network-based risk reduction interventions.