Peer Testing
syphilis
SYPHILIS
For the primary outcome, the number of verified syphilis tests per index conducted by alters was 0.05 (5/100) in the control arm, 0.51 (51/100) in S-SST arm, and 0.31 (31/100) in RL-SST arm. Compared to the control arm, both the S-SST (RR = 10.2, 95% CI:2.9–36.3) and the RL-SST arm (RR = 6.2, 95% CI 1.7–22.5) were associated with a significantly higher number of tested alters per index. Although no significant difference was found on the overall number of tested alters per index between S-SST and RL-SST arm, there were more primary alters in S-SST arm than in RL-SST arm (Table Primary outcomes analysis at the end of the studyRR: relative ratio; CI: confidence interval; SOC: standard-of-care; S-SST: standard syphilis self-testing delivery; RL-SST: referral link syphilis self-testing deliveryFigure The impact of the interventions varied by indexes’ age, number of male partners in the past three months, social network size, and syphilis self-testing history. Compared with the SOC arm, the S-SST arm increased the effect of peer testing in MSMs aged 30 years or less (RR = 21.7, 95% CI 3.4–139.9), amongst indexes with both one or less male partners (RR = 10.2, 95% CI 2.1–50.0) and indexes with multiple male partners (RR = 15.0, 95% CI 1.6–144.1) in the past three months, amongst indexes with smaller (RR = 14.9, 95% CI 2.2–100.1) and larger (RR = 6.9, 95% CI 1.4–34.8) MSM social circles, and amongst indexes who had never self-tested for syphilis (RR = 11.0, 95% CI 2.1–58.5). By contrast, RL-SST increased the effect of peer testing in MSMs aged more than 30 years (RR = 6.2, 95% CI 1.1–35.2), indexes who had one or less male partners (RR = 7.0, 95% CI 1.6–31.8), or who had a smaller MSM social circle (RR = 10.8, 95% CI 1.6–70.8) (Table 