The use of inappropriate anal douching tool associates with increased HIV infection among men who have sex with men: a cross-sectional study in Shenyang, China

BACKGROUND: Rectal douching (RD) is widely practiced by men who have sex with men (MSM), and is associated with increased risk of HIV infection. However, the mechanism of how RD increases the risk of HIV infection is not well understood, and there is limited data on RD behavior in MSM practicing anal sex in China. We examine the purpose of RD, its timing in relation to anal sex, the types of RD products used, and risky sexual behaviors among MSM reporting anal sex. METHODS: Between August 2017 and December 2018, a cross-sectional study was conducted among adult MSM in Shenyang, China. Data were collected on demographics, sexual behaviors, and RD for the most recent sexual intercourse by means of interviewer-administered face-to-face questionnaires. Blood samples were collected to test for antibodies to HIV and syphilis. Multivariable logistic regression models were used to assess the risk factors associated with HIV infection. RESULTS: A total of 515 eligible MSM participated in this survey (median age: 31 years). During the most recent anal intercourse, 28.3% (146/515) had condomless receptive anal intercourse (CRAI), 21.4% (110/515) practiced serosorting, and more than half (61.6%, 317/515) reported RD before or after anal sex. Of those practicing RD, 96.8% (307/317) conducted RD before sex, while 62.5% (198/317) conducted RD after sex. The douching devices used were primarily shower hoses (85.3%, 262/307), and relatively few MSM used commercial RD products (8.1%, 25/307) before sex. The prevalence of HIV-1 and syphilis was 11.7% and 13.2%, respectively. HIV infection was positively associated with RD, practicing RD before sex, the interaction between RD and CRAI using a shower hose for RD and other risk factors, practicing RD after sex, CRAI, using nitrite inhalants, main sexual role with males as bottom and syphilis infection. CONCLUSIONS: RD is popular among Chinese MSM. Improper noncommercial RD tools use (such as shower hose), the interaction effect between RD and CRAI associated with HIV infection. Public health workers and the MSM community should publicize scientific knowledge and prevention approaches relating to RD and HIV transmission to MSM. We recommend that further studies should be conducted to understand the detailed mechanism between RD and increased HIV prevalence. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-021-10276-z.