^aPain Research, Department of Surgery and Cancer, Imperial College, Chelsea and Westminster Hospital Campus, London, United Kingdom

^bPopulation Health Science, University of Dundee, Ninewells Hospital and Medical School, Dundee, United Kingdom

^cUniversity of Sydney Centre for Education and Research on Ageing, Concord Repatriation General Hospital, Concord, Australia

Corresponding author. Address: Pain Research, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital campus, 369 Fulham Road, London, SW10 9NH UK. Tel.: + 44 208 746 8816. E-mail address: [email protected] (A.S.C. Rice).

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Received October 13, 2015

Received in revised form November 09, 2015

Accepted November 10, 2015