Risk attitudes, risky sexual behaviours and willingness to test negative for syphilis using lottery-based financial incentives among Chinese men who have sex with men.

BACKGROUND: Individuals with risk-loving attitudes may be more likely to participate in high-risk sex and gambling. We investigated whether a lottery-based financial incentive to have a negative syphilis test may attract Chinese men who have sex with men (MSM) who practised risky sexual behaviours. METHODS: In July 2018, a national online cross-sectional survey was conducted in China. We collected information on willingness to participate in a lottery-based financial incentive where men were eligible if they tested negative for syphilis, and the minimum prize that would attract them to participate. We used a validated risk attitude scale which asked about the willingness to take risks in six domains, ranging from 0 (avoids taking risk) to 10 (fully prepared to take risks). To avoid multicollinearity, we used principal components analysis to create a 'risk attitude index'. Bivariable and multivariable logistic regression explored factors associated with willingness to test negative for syphilis. RESULTS: 699 MSM enrolled with a median age of 26 years (IQR: 23-30). 70% self-identified as gay and 52% reported ever testing for syphilis. 64% stated they were likely or very likely to test for syphilis linked with a lottery-based incentive. The median desired amount for the lottery had an expected value of ¥10 (US$1.50, IQR: ¥5-¥30). Men who had greater odds of willingness to participate in the lottery-based incentive were those scoring highest on the risk attitude index (adjusted OR (AOR) 2.6, 95% CI 1.5 to 4.3), those reporting more than one sexual partner in the last 3 months (AOR 1.7, 95% CI 1.2 to 2.4), those who had not used condoms during their last sex (AOR 1.5, 95% CI 1.0 to 2.2) and those who ever had group sex (AOR 1.5, 95% CI 1.0 to 2.2). CONCLUSION: Chinese MSM with higher risk attitudes and who reported riskier sexual behaviours indicated greater interest in the concept of a lottery-based incentive for syphilis testing. A lottery-based incentive may be a promising strategy for promoting condom use among risk-loving men.