[1] Alfred Hosp, Dept Gastroenterol, Melbourne, Vic, Australia
[2] Monash Univ, Cent Clin Sch, Melbourne, Vic, Australia
[3] Monash Univ, Dept Epidemiol & Prevent Med, Melbourne, Vic, Australia
[4] St Vincents Hosp Melbourne, Dept Gastroenterol, Melbourne, Vic, Australia
[5] Univ Melbourne, Dept Med, Melbourne, Vic, Australia
[6] Burnet Inst, Dis Eliminat Program, Melbourne, Vic, Australia
[7] Univ Queensland, Sch Publ Hlth, Brisbane, Qld, Australia
[8] ANZAC Inst Concord Hosp, Sydney, NSW 2139, Australia