About 20% of our sampled MSM in Hong Kong had experience of SDU in their lifetime. As compared to those without such experience, MSM with experience of SDU reported much higher prevalence of sexual risk behaviors (i.e., anal intercourse with non-regular sex partner and CAI) and other STIs. Many MSM frequently engaged in SDU, and SDU commonly involved group sex and CAI. Therefore, MSM with experience of SDU are of much higher risk of HIV infection.
At the time of the survey, 4% of all participants were on PrEP. Such prevalence was comparable to a representative MSM survey conducted in 2017 (3.6%) (3). Our results confirmed that MSM with experience of SDU had higher interest to use PrEP, as they reported much higher uptake than those without such experience (12.1% vs. 2.1%, p < 0.001). Mathematical models suggested that achieving 75% PrEP coverage among high-risk HIV-negative MSM in China would prevent 25.7% of new HIV infection among MSM (41). Given the high-risk profiles, MSM with experience of SDU should be priority group for future PrEP implementation. Strategies to increase PrEP access and coverage are hence needed for MSM with experience of SDU in Hong Kong.
This study also identified some issues among MSM PrEP users in Hong Kong. Similar to some western countries, over half (13/23) of the users obtained PrEP through internet or oversea clinics, probably due to high cost of obtaining PrEP in local clinics and limited coverage of the demonstration project (42). These PrEP users may encounter supply difficulties, which reduces their adherence and hence diminishes the effectiveness of PrEP (43). We found that five out of 14 daily PrEP users reported sub-optimal adherence to daily regimen, while three other users were on holiday PrEP. Future studies should explore reasons for sub-optimal adherence among local MSM PrEP users, especially those who obtained PrEP through online purchases or oversea clinics.
Among participants who were not on PrEP, about 60% of them were willing to use daily PrEP in the next six months. Such prevalence was higher than MSM in general in Hong Kong. The results also suggested that the current market rate for obtaining PrEP in Hong Kong ($8,000 per month) was not affordable for local MSM, as none of the participants were willing to pay such amount. Future PrEP implementation in Hong Kong should take potential users’ willingness to pay into consideration.
To achieve high coverage of PrEP, health promotion is needed even if affordable PrEP is made available in Hong Kong. Findings of this study provided some insights for promoting PrEP among Hong Kong MSM with experience of SDU. Similar to other studies, younger participants showed higher willingness to use PrEP (18). They may be more responsive to future PrEP promotion. Special attention should be given to those having anal intercourse with NRP in the last year, as they perceived a stronger need to protect themselves against HIV. Those who have taken up HIV testing in the last year also showed higher willingness to use PrEP. HIV testing and counseling may be an ideal setting to promote PrEP, as confirmed HIV-negative sero-status is a prerequisite for initiate PrEP, and users may already been motivated to take up HIV protective measures and should be more ready to use PrEP (44). Local NGO may play an important role in future PrEP implementation, as they are main providers of HIV testing services for local MSM (45).
This study examined the association between SDU patterns and willingness to use PrEP for the first time. Higher frequency of SDU, poly-use of psychoactive substances and CAI during SDU were associated with higher willingness to use PrEP. It is understandable as MSM having these behaviors during SDU were of higher risk of HIV infection, and they had stronger need to use PrEP to protect themselves against HIV. Demonstration studies showed that MSM may continue or even increase their high risk behaviors after using PrEP (46–48). Therefore, interventions promoting condom use/drug-cessation should be essential parts for future PrEP implementation program targeting MSM with experience of SDU to ensure the effectiveness of PrEP.
Our results also suggested that increasing positive attitudes toward PrEP, creating subjective norm supporting PrEP use, and enhancing perceived behavioral control of using PrEP are potential useful strategies to promote PrEP, as these factors were significantly associated with willingness to use PrEP. Health communication messages should emphasize PrEP is an effective strategy in preventing HIV during SDU. Future health promotion should also encourage MSM with experience of SDU to discuss PrEP with their significant others, so as to obtain support. Simplification of the procedures to obtain PrEP and provision of gay-friendly services may be useful strategies to enhance perceived behavioral control of using PrEP. In contrast to our hypothesis, negative attitudes such as concerns about psychoactive substances would reduce effectiveness, increase severity of side effects or risk of non-adherence, or lead to stigmatization originated from service providers was not significantly associated with willingness to use PrEP. Removing these negative attitudes may not be useful strategies to promote PrEP in this group.
This study was one of the first studies looking at PrEP use among Chinese MSM with experience of SDU. However, it had some limitations. First of all, participants were recruited by non-probabilistic sampling in the absence of sampling frame. As compared to a representative MSM survey in Hong Kong, our participants similar level of sexual risk behaviors, but higher HIV testing rate. Second, we were not able to obtain characteristics of participants who refused to join the study; selection bias might exist. The response rate was relatively higher than other published study involving MSM in China and outside China. Third, the results were self-reported, and the prevalence of SDU as well as risk behaviors during SDU may be under-reported, although anonymity should have reduced the bias. Fourth, we did not ask willingness to use PrEP among those without experience of SDU, and was not able to compare willingness/perceptions between those with and without such experience. Moreover, we did not ask participants’ willingness to use on-demand PrEP (49). The willingness to use PrEP may be underestimated. Finally yet importantly, this was a cross-sectional survey and could not establish causal relationship.