Discussion
syphilis, MSM
SYPHILIS, SECONDARY, RECRUITMENT
In this study, we found that peer distribution of syphilis self-testing improved syphilis testing uptake among MSM compared to standard-of-care. We evaluated different models for peer testing and found that person-to-person distribution resulted in a greater uptake of primary alter testing than a peer-led online referral system. To our knowledge, this is the first study to evaluate different models for syphilis peer testing and provides important insights into how to further increase uptake of syphilis testing among MSM in China.Our study showed that peer distribution of syphilis self-testing kits can improve syphilis testing uptake compared to referral for facility-based testing. We observed that indexes and alters in both intervention arms were more likely to provide test kits to their peers than those in the standard-of-care arm. This is consistent with the results in studies of secondary distribution of HIVST in China (Sha et al., Our study observed a relatively low rate of adverse outcomes among both indexes and alters during the study. The frequency of coerced testing, physical and verbal abuses among alters was low, which is consistent with studies on secondary distribution of HIVST in Malawi (Choko et al., Previous economic evaluation on syphilis self-testing showed that syphilis self-testing is cheaper than facility-based testing (Wang et al., This study has implications for policy and implementation. First, given that many facilities providing syphilis testing were completely or partially closed during COVID-19 restrictions, our study offers an innovative approach to distribute syphilis self-testing. Second, this study captures the identifiers of key indexes who could disseminate syphilis self-testing in social network among MSM. With this reference, health workers can tailor syphilis peer testing services among key populations. Furthermore, this study has laid the foundation for exploring novel approaches of peer distribution. Future studies should examine the index-alters social network ties and alters characteristics that predict higher distribution and acceptability of syphilis self-testing. Lastly, peer distribution of standard syphilis self-testing has lower costs for each alter tested. With the cost reduction of self-testing and minimal harm caused, we can extend this approach to other STI peer testing among key population in LMICs.Our study has several limitations. First, people’s social activities have been largely restricted due to COVID during our study period, which brought challenges to both recruitment and distribution amongst peer networks. Second, recruitment took place in specialist’s clinics, CBOs’ offices, and outreach venues. As such, our study might potentially exclude people who were less likely to connect with the CBOs. Lastly, we used a syphilis rapid test instead of the HIV/Syphilis rapid dual test used in other studies (Cheng et al., In conclusion, this RCT assessed the effectiveness of peer distribution of syphilis self-testing. The findings show that peer distribution of syphilis self-testing could increase syphilis testing uptake among MSM and provide evidence to help optimize syphilis peer testing services among key populations. This approach warrants further consideration as part of expanding syphilis self-testing.