[1] Hosp Gen Univ Gregorio Maranon, Serv Med Aparato Digest, Inst Invest Sanitaria Gregorio Maranon, Madrid, Spain
[2] Univ Complutense Madrid, Madrid, Spain
[3] Inst Salud Carlos III, Ctr Invest Biomed Red Enfermedades Hepat & Digest, Madrid, Spain
[4] Hosp Univ Ramon y Cajal, Dept Gastroenterol & Hepatol, Inst Ramon y Cajal Invest Sanitaria IRYCIS, Madrid, Spain
[5] WL Gore & Associates Ltd, Newark, NJ USA
[6] Gore & Asociados SL, Barcelona, Spain
[7] Univ York, York Hlth Econ Consortium Ltd, Enterprise House,Innovat Way, York YO10 5NQ, England