Sydney Medical School-Northern, Pain Management Research Institute, The Kolling Institute, Faculty of Medicine and Health, University of Sydney, Australia

Corresponding author. Address: Sydney Medical School-Northern, Pain Management Research Institute, The Kolling Institute, Faculty of Medicine and Health, University of Sydney, Sydney, NSW 2065, Australia. Tel.: 61 0409609208. E-mail address: [email protected] (M.K. Nicholas).

Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.