Exploring the diversity of sexual acts in Chinese men who have sex with men and its impacts on the risk of HIV and sexually transmitted infections

Objectives: High-risk sexual behaviour contributes to sexually transmitted infections (STIs), but the diversity of sexual acts in men who have sex with men (MSM) was understudied. We aimed to identify the diversity of sexual acts in Chinese MSM and its impacts on HIV/STI risk. Study design: Cross-sectional study. Methods: Between January and September 2022, the study was conducted in Xi'an, China, to identify sexual acts performed during the last sexual episode, which was measured by the Shannon diversity index. Results: Of the 931 MSM, 2.9 % tested positive for HIV, 5.7 % for syphilis, 13.6 % for gonorrhoea and 12.9 % for chlamydia. The Shannon diversity index for individual sexual acts was 1.609 (IQR 0.693–1.946), whereas the index for sexual act pairs was 1.386 (IQR 0–1.792). MSM infected with gonorrhoea exhibited significantly greater diversity in individual sexual acts (1.792 vs. 1.609) and sexual act pairs (1.609 vs. 1.386) than otherwise. Compared with MSM having one partner over the past 3 months, MSM with 2–5 partners was 69.7 % more diverse in individual sexual acts (aOR = 1.697, 1.489–1.935) and 59.4 % more diverse in sexual act pairs (aOR = 1.594, 1.401–1.811). For MSM with >5 partners, the corresponding percentages were 84.8 % (aOR = 1.848, 1.624–2.104) and 56.2 % (aOR = 1.562, 1.368–1.782). Compared with those who did not use saliva as a lubricant, MSM who did were less diverse in individual sexual acts (aOR = 0.763, 0.662–0.878) and sexual act pairs (aOR = 0.752, 0.654–0.866). Conclusion: MSM infected with gonorrhoea and those with multiple sexual partners are more diverse in sexual acts during sexual episodes.