[1] Lausanne Univ Hosp, Inst Social & Prevent Med IUMSP, Lausanne, Switzerland
[2] Univ York, Ctr Hlth Econ, York, N Yorkshire, England
[3] Univ Lausanne, Fac Business & Econ HEC, Lausanne, Switzerland
[4] Gastroenterol Beaulieu SA, Crohn & Colitis Ctr, Lausanne, Switzerland
[5] Lausanne Univ Hosp, Serv Gastroenterol & Hepatol, Lausanne, Switzerland
[6] Univ Hosp Zurich, Dept Gastroenterol & Hepatol, Zurich, Switzerland
[7] Helsana Grp, Dept Hlth Sci, POB 8081, Zurich, Switzerland