2020 Randomized Controlled Trial

  Gonorrhea and chlamydia are two common sexually transmitted infections (STI) that increase HIV risk among many key populations, including gay and bisexual men. However, most men are not tested, in part because of fees and low community engagement. A new study from researchers at the  University of North Carolina Project China evaluate an innovative testing strategy, pay-it-forward, to increase gonorrhea and chlamydia testing among gay men in China. The pay-it-forward model uses an initial funding pool to provide free gonorrhea and chlamydia tests to men as a gift, and then lets them decide whether they want to pay it forward to support other people’s testing. While this general concept has been used in many businesses, this study breaks ground in applying it to health.

  Pay-it-forward for health started in 2017 as a small pilot led by the UNC Project-China team (see here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6347395/). Building on this pilot, UNC postdoctoral fellow Fan Yang, medical student Philip Zhang, and UNC Project China Assistant Director Weiming Tang designed a randomized controlled trial (RCT). The purpose of the RCT was to assess the effectiveness of pay-it-forward in increasing test uptake in contrast to two comparison groups – a standard of care group, where tests were offered at fixed regular prices; and a pay-what-you-want group, where tests were offered free and men who tested could pay any desired amount for the tests they received. This design was intended to understand whether pay-it-forward is superior to a standard-of-care approach by increasing test uptake by at least 20% among this population. Also, it aimed to tease out whether the same effect can be achieved by merely making prices flexible, as implemented in the pay-what-you-want comparison group.

  The team built this study within three HIV testing sites in Beijing and Guangzhou, in collaboration with Blued, the largest gay online dating mobile application in China, and Zhitong LGBT Center which serves gay men and other LGBTQ individuals in the metropolitan Guangzhou areas. Many community volunteers enthusiastically took part in the design, piloting, and implementation of the randomized trial study.

  The RCT showed that pay-it-forward increased the gonorrhea and chlamydia screening test uptake by 38% compared to the standard of care. Within the pay-it-forward arm, 95% of men chose to donate some amount towards other’s testing. A related qualitative analysis examined reasons why gay men were more willing to test through pay-it-forward. The qualitative analysis concluded some participants were motivated by the contagious kindness pay-it-forward has generated, while others were driven by the free services which were otherwise unaffordable. A 30-year old pay-it-forward participant commented “This is a type of passing forward of trust…normally when you buy something, it’s a market exchange, one hand pays and one hand takes. But this has sentiment” after receiving his pay-it-forward test.

Dr. Stefan Baral, an Associate Professor at Johns Hopkins not involved in the study, noted, “Intersecting biological, network, and structural factors work together to increase STI incidence among gay men in resource-constrained environments. The study by Yang et al. provides critical data to inform STI testing interventions in this group, underlining the need for subsequent research and action.” Currently, the team have several studies planned to leverage the Pay-it-forward to improve other preventive health service uptake, including vaccination in rural community health centers in China.

Research Abstract



WHO recommends that men who have sex with men (MSM) receive gonorrhoea and chlamydia testing, but many evidence-based preventive services are unaffordable. The pay-it-forward strategy offers an individual a gift (eg, a test for sexually transmitted diseases) and then asks whether they would like to give a gift (eg, a future test) to another person. This study examined the effectiveness of a pay-it-forward programme to increase gonorrhoea and chlamydia testing among MSM in China.

We did a randomised controlled superiority trial at three HIV testing sites run by MSM community-based organisations in Guangzhou and Beijing, China. We included MSM aged 16 years or older who were seeking HIV testing and met indications for gonorrhoea and chlamydia testing. Restricted randomisation was done using computer-generated permuted blocks. 30 groups were randomised into three arms (1:1:1): a pay-it-forward arm in which men were offered free gonorrhoea and chlamydia testing and then asked whether they would like to donate for testing of prospective participants, a pay-what-you-want arm in which men were offered free testing and given the option to pay any desired amount for the test, and a standard-of-care arm in which testing was offered at ¥150 (US$22). There was no masking to arm assignment. The primary outcome was gonorrhoea and chlamydia test uptake ascertained by administrative records. We used generalised estimating equations to estimate intervention effects with one-sided 95% CIs and a prespecified superiority margin of 20%. The trial is registered with ClinicalTrials.gov, NCT03741725.

Between Dec 8, 2018, and Jan 19, 2019, 301 men were recruited and included in the analysis. 101 were randomly assigned to the pay-it-forward group, 100 to the pay-what-you-want group, and 100 to the standard-of-care group. Test uptake for gonorrhoea and chlamydia was 56% (57 of 101 participants) in the pay-it-forward arm, 46% (46 of 100 participants) in the pay-what-you-want arm, and 18% (18 of 100 participants) in the standard-of-care arm. The estimated difference in test uptake between the pay-it-forward and standard-of-care group was 38·4% (95% CI lower bound 28·4%). Among men in the pay-it-forward arm, 54 of 57 (95%) chose to donate to support testing for others.

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