This cross-sectional study of 515 MSM in Shenyang, China reports the proportion of and reasons for practicing RD among MSM in China. It investigated the impacts of RD products, douching liquid types, and the timing of RD on HIV infection. We found that using a shower hose to assist RD was positively associated with the odds of HIV-1 infection among MSM. This finding contributes to our understanding of RD behavior and the risks of HIV infection among MSM. It also helps to clarify the possible reasons for the high HIV disease burden of MSM in China, and our study provides first-hand evidence to include in future publicity materials and educational activities about the risks associated with RD and HIV infection among MSM.
This study found that the proportion of RD among MSM in Shenyang, a city with a lower level of GDP than other cities in China, was over 60%, similar to the percentage reported for Beijing (59.3%) [16]. These figures suggest that RD might be a common practice among MSM in urban China whatever their economic level. The prevalence of RD behavior among MSM in China is close to that of the USA (66%), Kenya (63%) [5, 6], the UK, Brazil, and France (53.4–54.3%)[4, 7, 8], but greater than that in Peru (18.2–27.0%) [17, 18] and the Netherlands (13.6–46%)[19, 20]. Despite this high prevalence among MSM worldwide, scientific data for and knowledge of RD in the Chinese MSM population is still poor. Around a quarter of MSM in the USA did not know how to douche the rectum correctly [21], and more than 94% of MSM in Brazil had not received any kind of professional instruction [7]. Currently, there is no authoritative information on RD for MSM in China. The disparity between the prevalence of RD and the lack of instruction about it highlights the importance of delivering accurate and relevant information about RD to the MSM population via social media.
This study found that RD is positively correlated with the odds of HIV infection (AOR = 2.8) in MSM participants, consistent with previous findings from the USA and Europe and a recent meta-analysis [9, 20–23]. We also found that the use of a shower hose (vs. commercial douching products/bulb syringe) and before/after anal intercourse RD (vs. no RD before/after sex) correlated with increased odds of HIV infection. Shower hoses are not expressly designed for RD as they have irregular edges (Fig. 2). The process of using a shower hose to complete RD may cause damage to the perianal skin, and hence increase the risk of HIV infection. In this survey, more than 85% of MSM participants used the shower hose to flush their anus, which is significantly higher than in foreign MSM populations. According to our study results, health workers and MSM community based organizations (CBOs) should widely publicize the potential for this type of RD to increase HIV infection in the MSM community. In addition, this study found that most MSM conducted pre-anal intercourse RD using tap water. Due to the difference in fluid osmotic pressure inside and outside the rectal epithelial cells, the latter are in a fully filled state following RD, and the risk of rupturing them is increased during anal sex. Water-based enema solutions are typically hypotonic and exert a lower osmotic pressure compared to the contents of the colon. As a result, excess water may be absorbed by epithelial cells, leading to water toxicity and cell lysis.[24] So enemas consisting of saline solution are recommended for MSM who practice RD frequently. For the benefit of MSM who engage in RD, it is recommended that they receive proper educational materials on how to select the most appropriate douching products and liquids so as to reduce the risk of HIV and sexually transmitted infections (STIs) resulting from rectal mucosal injuries.
This study found that, compared to MSM who do not perform RD, MSM who do use RD engaged in a greater proportion of bottom and versatile roles during anal sex. To exclude its mediating effect on HIV infection, we used two multivariable logistic models in this study, and found that whether adjusted the variable of sexual role RD is positively associated with increased odds of HIV infection among MSM participants. The results of our analysis have given us more reliable evidence of the association between RD behavior and HIV infection in the MSM population.
Understanding the reasons why MSM practice RD is important for promoting HIV-related education and conducting further studies. Over 95% of MSM participants did so because they wanted to remain clean and hygienic before and/or after having anal intercourse and to increase pleasure during sex. A proportion (14.6%) were under the misconception that RD could wash semen away from the rectum and prevent HIV infection and STIs. This suggests that MSM participants were very concerned about their own health and about preventing HIV infection and other sexually transmitted diseases (STDs). Given the positive correlation between RD behavior and a willingness to use rectal microbicides among Peruvian MSM [18], our study findings indicate that Chinese MSM are likely to be good candidates to be recruited to use rectal microbicide enemas for HIV prevention.
This study also found that factors contributing to HIV-1 infection include: (i) condomless anal intercourse; (ii) using nitrite inhalants before anal intercourse; and (iii) not serosorting in the most recent anal intercourse. These findings are consistent with those of international peer reports [9, 25]. It is worth noting that previously there was a lack of evidence to support the implementation of serosorting behavior to prevent HIV infection in MSM in China, although the Chinese Center for Disease Control and Prevention (China CDC) had issued related serosorting guidelines for MSM in 2016. Hence, in China, pertinent interventions, such as promoting serosorting among MSM who practice RD and the promotion of partner notification, are urgently needed. The results of this study will help China and other countries in a similar situation to promote serosorting measures among MSM to reduce HIV infection.