Table 1.

Overview of themes demonstrating diverging expert opinions regarding social media recruitment.

Theme	Benefits (+)	Challenges (−)
Resources needed to conduct social media recruitment	Cost-effective and rapid recruitment, especially for large samples Effective in low population density settings and over a large geographical area Easy to conduct and can be done in-house	Does not lead to cost savings as a full-time employee may need to be hired to manage social media recruitment Setting up and implementing a social media recruitment strategy is very time-consuming. Compared to onsite recruitment, social media recruitment requires additional financial and human resources
Representativeness of social media recruitment	Easier to target specific populations For very specific target group, it is more important to reach them at all rather than trying to get a representative sample Reach people you would not otherwise reach as some are only available on the internet Good representation of older and younger adults	Not representative of the study population, as certain demographic groups are overrepresented, while others are underrepresented, especially if the study requires a high number of participants Selection bias is a risk for any study
Web-based community building as part of social media recruitment	Direct contact between researcher and participant is highly valued by participants The possibility to stay in contact with the participants is good for follow-up studies and participant retention Interaction between participants gives them a sense of security and reassurance, and they feel less alone with their disease Enables more targeted recruitment efforts Participants disclose more web-based information than in a face-to-face conversation	Building a web-based community for the participants is associated with higher costs Unblinding of participants may have a negative impact on the quality of the study Social pressure to participate in the study if exerted by personal contacts or within the community Personal contact with the doctor is very important for building trust, especially in the clinical setting
Privacy considerations regarding social media recruitment	The use of social media should be considered a risk of daily life No privacy issues if: advertising on social media does not involve coercion users provide the information intentionally or voluntarily	Particular risks in recruiting via social media The problem of inferential targeting and user profiling through artificial intelligence algorithms used by social media companies leads to privacy violations Uncertainty about what can be done in terms of data protection