[1] London North West Univ Healthcare NHS Trust, Dept Otolaryngol, London, England
[2] South Tyneside & Sunderland NHS Fdn Trust, Dept Otolaryngol, Sunderland, Durham, England
[3] Kings Coll London, Dept Med Educ, London, England
[4] Imperial Coll London, Dept Metab Digest & Reprod, London, England