Greaves Kate E., Fairley Christopher K., Engel Jaimie L., Ong Jason J., Rodriguez Elena, Phillips Tiffany R., Chow Eric P. F. (2022) Sexual mixing patterns among male–female partnerships in Melbourne, Australia. Sexual Health 19, 33-38.
Background:Individuals who have both opposite- and same-sex partners have the potential to pass sexually transmitted infections (STIs) between high- and low-risk populations. Our aim was to examine assortative sexual mixing in terms of same-sex activity among male–female partnerships.
Methods:This was a retrospective repeated cross-sectional study of male–female partnerships attending the Melbourne Sexual Health Centre (MSHC) from 2015 to 2019. Sex of sexual partners was collected via computer-assisted self-interview. We calculated the proportion of partnerships where at least one individual reported same-sex partners in the previous 12 months and the degree of assortativity by bisexuality.
Results: A total of 2112 male–female partnerships (i.e. 4224 individuals) were included, with a median age of 27 years (IQR 23–31). Overall, 89.3% (1885/2112) of male–female partnerships did not report any other same-sex partners; however, in 9.5% (201/2112) of partnerships, same-sex partners were reported by one individual and in 1.2% (26/2112) of partnerships, both individuals reported same-sex partners. Bisexuality appeared to be slightly assortative in male–female partnerships (r = 0.163, 95% CI: 0.150–0.176; P < 0.001).
Conclusion: One in 10 individuals in male–female partnerships had at least one same-sex partner within the previous 12 months. Individuals were minorly selective by bisexuality, suggesting the patterns of bisexual mixing in male–female partners are more variable and this may have a significant impact on STI transmission in heterosexual populations.