[1] Univ Nottingham, Sch Med, Div Epidemiol & Publ Hlth, Nottingham, England
[2] Ninewells Hosp, Dundee, Scotland
[3] Univ Nottingham, Nottingham Digest Dis Ctr, Sch Med, Nottingham, England
[4] Univ Nottingham, NIHR Nottingham Digest Dis Biomed Res Ctr, Sch Med, Nottingham, England