Footnotes

• Contributors GZ was responsible for design and conceptualisation of the study, analysis and interpretation of the data, and revising the manuscript for intellectual content. FM was responsible for analysis and interpretation of the data, and drafting the manuscript. ST was responsible for conceptualisation of the study, analysis and interpretation of the data, and revising the manuscript for intellectual content. All authors gave final approval of the version to be published.

• Competing interests GZ received travel grants from Grifols and Pfizer for participation in scientific conferences and meetings. FM received travel grants from Grifols and Astellas for participation in scientific conferences and meetings. ST received travel grants from Grifols, Astellas and Pfizer for participation in scientific conferences and meetings. The Institution of ST received money from Pfizer for educational activities on neuropathic pain. The Institution of ST received EFIC Grünenthal Grant 2010.

• Patient consent Obtained.

• Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Carolyn Gabriel, London, UK.