Maximizing Response Rates to Ads for Free At-Home HIV Testing on a Men-for-Men Geosocial Sexual Networking App: Lessons Learned and Implications for Researchers and Providers.

Internet-based recruitment can be effective in reaching large numbers of geographically diverse individuals. Geosocial sexual networking apps on smartphones have emerged as the modal way in which men who have sex with men (MSM) meet sex partners, and as venues for sexual health research. We report on the performance of three types of ads-text-only, text with male figure (no face), and text with male figure (with face)-used on a geosocial sexual networking app to advertise free at-home HIV testing and to enroll in an online study. We ran five 2-week-long ads on a popular MSM geosocial app between fall 2017 and spring 2018 (~2.19 million impressions). Ads were evaluated in terms of the click-through rate (CTR = advertisement clicks/advertisement impressions), conversion rates (CR = number of enrolled participants/ad-generated clicks), cost per enrolled participant, and demographic composition of survey respondents. We enrolled = 4,023 individuals, = 2,430 of whom completed HIV testing-$6.21 spent on advertising per participant enrolled and $10.29 spent for everyone who completed HIV testing. Cost per enrolled participant was associated with the of the ad used-ads featuring male figures (with or without a face shown) were more cost efficient than ads featuring text alone. These ads also outperformed text-only ads across a range of metrics, including responsiveness among younger MSM as well as MSM of color. Advertising materials that combine text with images may have greater appeal among priority populations.