[1] Airedale Dist Gen Hosp, Keighley BD20 6TD, W Yorkshire, England
[2] Univ E Anglia, Sch Environm Sci, Norwich NR4 7TJ, Norfolk, England
[3] Hlth Protect Agcy, Resp & Syst Infect Dept, Ctr Infect, London NW9 5EQ, England
[4] Univ Leeds, Ctr Biostat & Epidemiol, Leeds LS9 7TF, W Yorkshire, England
[5] St James Univ Hosp, No & Yorkshire Canc Registry, St Jamess Inst Oncol, Leeds LS9 7TF, W Yorkshire, England
[6] St James Univ Hosp, Informat Serv, St Jamess Inst Oncol, Leeds LS9 7TF, W Yorkshire, England