Online recruitment of study participants

On 17 November 2020, more than 70 colleagues discussed 'Online recruitment of study participants’ in a webinar organized by RIHS. This webinar was the first chapter of the RIHS digital health research series. In this session, Marleen van Gelder (PRIDE study), Maaike Gerritse (DECISION study) and Janet den Hollander (Healthy brain study) shared their experiences with online recruitment of study participants.  Jolt Roukema shared the view of the Medical-Ethical Review Board Arnhem-Nijmegen on online recruitment. The webinar was hosted by Tom van de Belt. If you missed it: the session is available online.

Disappointing participation rates were one of the main reasons to switch to the recruitment of study participants via social media. All speakers favoured this enrichment of their recruitment strategy, since it was (very) successful in improving the inclusion rates for their studies. For example, the Facebook ads in the PRIDE study resulted in new participants on a daily basis, which is more than via offline recruitment strategies. Facebook ads in the DECISION study also delivered new study participants, although the inclusion rate remained comparable to normal inclusion strategies.

One of the greatest benefits of online recruitment is the ability to reach out to your specific target population, starting by choosing the right media platform. All speakers in this Webinar used Facebook, as their target population was most active on this media platform. Interestingly, the characteristics of the participants they recruited via social media differed from ‘classically-recruited’ participants. Demographics such as age, body mass index, and educational level were different. By this, recruitment via social media has the potential to improve the external validity of your study!

As with everything, online recruitment via social media has some potential disadvantages. For example, online advertisements can be costly. In the presented studies, the costs differed from €10 to €112 per included participant. The costs can be reduced by more attractive advertisements (“content is king”), targeting the ads to a specific population, use study participants as promotors, simplifying your recruitment methods, and be clear about what is in it for them (incentives). Another potential disadvantage is that participants recruited via social media may have a lower commitment to your study, which could lead to higher loss to follow-up.

The Medical-Ethical Review Board (Dutch: CMO) Arnhem-Nijmegen is enthusiastic about all new methods aimed at increasing participation rates, including online recruitment of study participants. Be aware that for WMO research, you will always need CMO approval for all online content. Besides, keep in mind that your advertisements cannot be too promotional and they do not replace the subject information sheet (Dutch: PIF). For non-WMO research, the most important requirement is that you apply to the General Data Protection Regulation (Dutch: AVG). The privacy officer of the hospital can help you if you have any questions about this.

Written by Tessa Schoot and Yannick de Korte

RIHS PhD Council