[1] Hosp Univ Vall Hebron, Casellas Digest Syst Res Unit, Barcelona 08035, Spain
[2] Compiejo Hosp Donostia, Serv Aparato Digest, San Sebastian, Spain
[3] Hosp Univ Virgen Candelaria, Serv Aparato Digest, Tenerife, Spain
[4] Hosp Figueres, Figueres, Spain
[5] Hosp Lluis Alcanyis, Valencia, Spain
[6] Secc Aparato Digest, Menorca, Spain
[7] Hosp Univ Canarias, Serv Aparato Digest, Tenerife, Spain
[8] Prague Technol San Sebastian, Fdn Inbiomed, San Sebastian, Spain
[9] Hosp Univ Tarragona Joan XXIII, Med Interna Serv, Tarragona, Spain
[10] Univ Oviedo, Hosp Cent Asturias, Serv Digest, E-33080 Oviedo, Spain