The Internet can efficiently reach large numbers of patients. Free and fee-based recruitment strategies both have merits. Facebook communities are a rich resource for Internet researchers 1).

1)
Davies B, Kotter M. Lessons From Recruitment to an Internet-Based Survey for Degenerative Cervical Myelopathy: Comparison of Free and Fee-Based Methods. JMIR Res Protoc. 2018 Feb 5;7(2):e18. doi: 10.2196/resprot.6567. PMID: 29402760; PMCID: PMC5818678.