1. Department of GastroenterologyPortuguese Oncology Institute of PortoPortoPortugal
2. Department of GastroenterologyCentro Hospitalar de LeiriaLeiriaPortugal
3. University of Kansas School of MedicineKansas CityUSA
4. Department of GastroenterologyVeterans Affairs Medical CenterKansas CityUSA
5. Center for Health Technology and Services Research (CINTESIS)University of PortoPortoPortugal