Background

Globally, men who have sex with men (MSM) continue to be disproportionately affected by human immunodeficiency virus (HIV) [1, 2]. Homosexual behavior is an important route of HIV transmission in Zhengjiang province, China which reoported an estimated 400,000 MSM [3,25,26,27,28]. We hypothesized that the factors affecting condom use when MSMW were with males and females would be both different and independent. However, our study showed that inconsistent condom use with males was the most important risk factor for ICUF with the highest risk score. MSM had special subculture of condom use in these years as the development of HIV prevention and their psychological characteristics [29]. MSMW is more vulnerable to condom culture than heterosexuality men which will also impacted condom use with females. Furthermore, MSMW reported insertions into males, which might be the reason for consistent condom use behavior between males and females [10]. Thus, interventions promoting condom use with males (knowledge of HIV, the attitude to condoms, self-efficacy, intention, and being skilled in the use of condoms) might prevent ICUF [30].

Living in local residence less than 6 months, having more than one male partners and never heard PEP were predictors of ICUF with the same risk score. The Province is economically well-developed in China and a large amount of funds and manpower are invested for MSM intervention. The three “90%” strategy are improved rapidly in these years with 86%, 95% and 97% in the province in 2022 [32, 33]. MSM in Chinese reported lower rate of PEP knowlege than in many countries [33]. The relationship between PEP awareness and condom use may be confusing, but it can be interpreted from a health awareness perspective. Those never hearding PEP might be kind of poplulation who are not aware of HIV infection, or have just entered the gay group who have not received enough HIV intervention. This kind of group always report risky sexual behavior, whatever with male or females. We suggest further research to detecte deep reseaon of condom use with females considering more factors.

Notably, we found no relationship between ICUF and interventions on dating app “Blued”. An digital technologies are commonly used based on apps, such as "Wechat", "Tencent", "Blued" in China [34]. App “Blued” is an dating app for finding sexual partners targating MSM and always used by govenment for HIV intervention. In fact, intervention on condom use was complimented in the recent ten years, but not special for MSMW, which could be responsible for the result. So, it should be considered the strategy targeting MSMW should be considered by govenment and make good use of internet.

Bisexual MSM are the principal bridge group for HIV transmission to females [35, 36]. In this study, compared to bisexual MSMW, heterosexual/unsure MSMW were more likely to be younger, less well-educated, and unmarried. Heterosexual/unsure MSMW reported less risky behavior with males and females in the last 6 months, more consistent condom use with males, and more commercial sex. Moreover, MSMW who are unsure of their sexual orientation also need attention; Support from family, relatives, friends, govenment was minimal and risky behavior might be high, given the traditional Chinese family culture [25, 37].

Limitations and strengths: This study had several limitations. First, the participants might not be representative of all MSM and MSMW populations in Zhejiang Province. MSMW were not randomly sampled, instead taking part on a volunteer basis (self-selection); this may have caused selection bias. Second, due to the cross-sectional design, causality could not be inferred; thus, a cohort study is needed to validate our findings. Finally, some predictors of heterosexual behavior and unprotected sex with women may have been missed. Further research should include psychological, sexual, cultural, and additional behavior indicators. As a strength of the study, to minimize bias, the introductory section of the questionnaire emphasized the need for commitment from the participant to ensure high-quality data. Also, all questionnaires were checked and revised if input errors or missing data were identified.

Conclusion

A relatively high rate of heterosexual behavior was observed among MSM in Zhejiang Province. We identified four predictors of ICUF in MSMW, of which inconsistent condom use with men was the most important. In an independent cross-sectional study, the high-risk group had high a rate of ICUF. Risk reduction intervention programs should focus on MSM who report commercial sex with men; these individuals are likely to engage in both heterosexual behavior and unprotected sex.