*Department of Surgery and Cancer, Imperial College London
†Department of Pain and Anaesthesia, Barts Health NHS Trust, London, UK
A.F. designed the study using data obtained from the National Centre for Social Research, wrote the statistical analysis plan, cleaned and analyzed the data, and drafted and revised the paper. He is the guarantor. H.C.W. assisted with the statistical design, statistical analysis, and revisions to the draft paper. R.M.L. and L.J.D. contributed to the design of the study and revised the draft paper.
Dr Langford reports personal fees from Grunenthal, grants and personal fees from Napp/Mundipharma, personal fees from Pfizer, personal fees from Astrazeneca, personal fees from BioQuiddity, personal fees from The Medicines Co, outside the submitted work. There are no other competing interests to report by any of the authors.
Reprints: Alan Fayaz, MA, MBBS, MRCP, FRCA, Department of Surgery and Cancer, Imperial College London, W2 1NY (e-mail: [email protected]).