Improving web-based respondent-driven sampling performance among men who have sex with men in the Netherlands

Respondent-driven sampling (RDS) uses the social network of participants to sample people of populations that can be challenging to engage. While in this context RDS offers improvements on standard sampling methods, it does not always generate a sufficiently large sample. In this study we aimed to identify preferences of men who have sex with men (MSM) in the Netherlands regarding surveys and recruitment to studies with the subsequent goal of improving the performance of web-based RDS in MSM. A questionnaire about preferences with respect to various aspects of an web-based RDS study was circulated among participants of the Amsterdam Cohort Studies, a study among MSM. The duration of a survey and the type and amount of participation reward were explored. Participants were also asked about their preferences regarding invitation and recruitment methods. We used multi-level and rank-ordered logistic regression to analyze the data and identify the preferences. The majority of the 98 participants were older than 45 years (59.2%), were born in the Netherlands (84.7%), and had a university degree (77.6%). Participants did not have a preference regarding the type of participation reward, but they preferred to spend less time on a survey and to get a higher monetary reward. Sending a personal email was the preferred option to getting invited or inviting someone to a study, while using Facebook messenger was the least preferred option. There are differences between age groups: monetary rewards were less important to older participants (45+) and younger participants (18-34) more often preferred SMS/WhatsApp to recruit others. When designing a web-based RDS study for MSM, it is important to balance the duration of the survey and the monetary reward. If the study takes more of a participants time, it might be beneficial to provide a higher incentive. To optimize expected participation, the recruitment method should be selected based on the targeted population group.Author summary: In the Netherlands, men who have sex with men (MSM) are more likely to acquire HIV than the general population. However, due to stigmatization, some individuals of this population are hard to engage with standard sample methods. Respondent-driven sampling (RDS) can be used to recruit these people and subsequently obtain a representative sample of a population. RDS is a sampling method that uses social networks of participants to recruit others. Here, we used a questionnaire to find preferences of MSM regarding duration and incentives of surveys and recruitment methods to improve the performance of web-based RDS in this population. We found that participants prefer to take part in a study that is shorter and offers a higher monetary reward. Thus, it might be beneficial to provide a higher reward if a study takes more time. Furthermore, we found that a personal email was the preferred option to get invited or invite someone to a study. However, there are differences between age groups, with younger men having a higher preference for SMS/WhatsApp invitations than older men. Therefore, the recruitment method should be chosen depending on the specific subgroup of MSM targeted in a study.