Association between rectal douching and HIV acquisition: the mediating role of condom use and rectal bleeding in a national online sample of Chinese men who have sex with men.

OBJECTIVES:Previous studies have demonstrated that rectal douching (RD) is associated with HIV acquisition among men who have sex with men (MSM). However, the precise mechanism underlying the association between RD and HIV remains unclear. METHODS:We recruited participants over WeChat from October 2017 to October 2018. Respondents received mailed HIV self-testing kits, uploaded images of HIV self-test results and completed an online electronic questionnaire simultaneously. The questionnaire assessed sociodemographic characteristics, RD practices and sexual risk behaviours. HIV status was measured as the result of the HIV self-testing. The Baron and Kenny statistical method was used to assess the association between RD and HIV, controlling for condomless anal intercourse (CAI) and rectal bleeding. RESULTS:Of 1365 participants, 39.93% (545/1365) reported RD in the past 6 months, 60.07% had multiple male sexual partners and 43.08% had CAI in the past 6 months. The prevalence of HIV, based on self-testing, was 3.37% (46/1365). Multivariable logistic analysis showed RD was significantly associated with bottom sexual role (adjusted OR (aOR) 14.0; 95% CI 9.8 to 20.2), having multiple male sexual partners (aOR 1.8; 95% CI 1.4 to 2.2), CAI (aOR 1.3; 95% CI 1.0 to 1.6), rectal bleeding (aOR 2.0; 95% CI 1.6 to 2.6) and HIV infection (aOR 1.9; 95% CI 1.0 to 3.4). Baron and Kenny analysis found both CAI (aOR 2.2; 95% CI 1.2 to 4.1) and rectal bleeding (aOR 1.9; 95% CI 1.0 to 3.4) play a mediating role in the association between RD and HIV. CONCLUSIONS:Our study results confirmed the relationship between RD and HIV, and found CAI and rectal bleeding mediated HIV infection in Chinese MSM who douched. Strategies should be encouraged to strengthen health education and reduce high-risk sexual behaviour in order to reduce the risk of HIV in MSM who use enemas. Rectal microbicides may represent an efficient means of providing HIV prophylaxis among MSM.