1 Centre for Health Technology Evaluation, National Institute for Health and Care Excellence (NICE), Manchester, UK, M1 4BT.
2 Centre for Health Technology Evaluation, National Institute for Health and Care Excellence (NICE), Manchester, UK, M1 4BT. Electronic address: ross.dent@nice.org.uk.
3 Centre for Health Technology Evaluation, National Institute for Health and Care Excellence (NICE), Manchester, UK, M1 4BT; Addenbrooke's Hospital, Cambridge, UK.