Use of Facebook, Instagram, and Twitter for recruiting healthy participants in nutrition-, physical activity–, or obesity-related studies: a systematic review

Background There are limited systematic reviews exploring the use of social media for recruiting participants specifically for nutrition, physical activity, and obesity related studies. Objective To conduct a systematic review on the effectiveness of using social media (Facebook, Instagram, and Twitter) for recruiting healthy participants in nutrition, physical activity, or obesity related studies. Design Studies were identified from five databases and included if they reported the number of participants recruited by social media (Facebook, Instagram, or Twitter) vs traditional (printed, email, etc.). The effectiveness of recruitment was compared between methods by study procedures (in-person vs online procedures). The cost-effectiveness of methods was also explored. The protocol was published in the Prospero database (ID# CRD42020204414). Results Twenty-six studies were included. Among studies with both types of recruitment methods, 49% of the sample was reached through traditional methods, 40% through social media, and the rest by other methods. For in-person study procedures, the median number of participants recruited using social media was 19 (range 3-278) and for online study procedures, it was 298 (range 3-17,069). Median recruitment cost using social media (n = 14 studies) was ${\$}$11.9 (range ${\$}$0-517) per participant while this varied considerably for traditional methods depending on how it was calculated (${\$}$214, ${\$}$18.9-${\$}$777). The ratio of participants reached vs recruited was 0.12%; the overall ratio of participants interactions vs recruited was 21.2%. Conclusion For in-person study procedures, traditional recruitment methods were more effective than social media but for online study procedures, about half reported that social media was more effective. While more potential participants were reached through social media, only 21.2% of those who interacted with ads were enrolled. With the increased use of social media, their use for recruitment may be more frequent; therefore, future reviews may show different results.