Patient preferences for inflammatory bowel disease treatments: protocol development of a global preference survey using a discrete choice experiment oleh Elise Schoefs, Séverine Vermeire, Séverine Vermeire, Marc Ferrante, Marc Ferrante, João Sabino, João Sabino, Bram Verstockt, Bram Verstockt, Luisa Avedano, Maria Stella De Rocchis, Magdalena Sajak-Szczerba, Roberto Saldaña, Noortje Straetemans, Noortje Straetemans, Martina Vandebroek, Rosanne Janssens, Isabelle Huys