Expanding Syphilis Test Uptake Using Rapid Dual Self-Testing for Syphilis and HIV among Men Who Have Sex with Men: A Multi-Arm Randomized Controlled Trial in China

Background: Low syphilis testing uptake is a major public health issue among men who have sex with men (MSM) in many low- and middle- income countries. Syphilis self-testing (SST) may complement and extend facility-based testing. Objective: To evaluate the effectiveness and costs of providing SST on increasing syphilis testing uptake among MSM in China. Design: Three-arm randomized; controlled trial with concealed allocation. (Chinese Clinical Trial Registry: ChiCTR1900022409) Setting: Online. Participants: 451 MSM were recruited from 124 cities in 26 Chinese provinces. Intervention: Standard SST arm, lottery incentivized SST arm (1 in 10 chance to win $15 if they tested for syphilis), and standard-of-care arm. Both SST arms were offered free syphilis/HIV self-test kits at monthly intervals via mail. Measurements: The proportion of participants who tested for syphilis during the 6-month trial period and confirmed with photo-verification. Results: The proportion of men who had at least one syphilis test during the trial period was 63.4% (95% CI: 54.9 to 71.3) in the standard SST arm, 65.7% (95% CI: 57.1 to 73.6) in the lottery-incentivized SST arm, and 14.7% (95% CI: 9.2 to 21.8) in the standard-of-care arm. The estimated difference in proportions between the standard SST and standard-of-care arm was 48.7% (95% CI: 37.7 to 58.4). The majority (78.5%, 95% CI: 72.0 to 84.1) of syphilis self-testers reported never testing for syphilis. The cost per person tested was $26.55 for standard SST, $28.09 for the lottery incentivized SST, and $66.19 for the standard-of-care. Limitation: The impact of COVID restrictions may have accentuated demand for decentralized testing. Conclusion: Compared to standard-of-care, providing SST significantly increased the proportion of MSM testing for syphilis in China, particularly among men who had never tested for syphilis, and was cheaper (per person tested). Primary Funding Source: National Natural Science Foundation of China (81772240).