Table 1 Characteristics of participants in the focus group discussions and semi-structured interviews (n participants = 20, n interviews = 19)

Focus group discussion 1 (n participants = 5)

One representative of a data infrastructure organization active on a global level, one EC representative active in Belgium, one investigator (who was also an EC representative) involved in a pan-European organization, and two patient organization representatives active at a pan-European level.

Focus group discussion 2 (n participants = 6)

EC representatives were active in Belgium (n = 3), Denmark (n = 1), Lithuania (n = 1), and the Netherlands (n = 1). Two representatives were also active at a pan-European level or in a national umbrella organization.

Semi-structured interviews (n participants = 9, n interviews = 8)

Regulators were active in Austria (n = 1), Finland (n = 1), Italy (n = 1), Lithuania (n = 1), and the Netherlands (n = 1). Two regulators were also involved in a pan-European organization. Representatives of the pharmaceutical industry were involved in clinical research on a Belgian (n = 1), European (n = 1), and global (n = 2) level.