Footnotes

• Contributors CD designed the data collection tool. CD, KN and SP collected and validated the data and revised the article. DV monitored data collection and validation for Sunderland. IE-G monitored data collection and validation for Middlesbrough. James Talks initiated the multi-centre project, supervised the data collection across sites and revised the article. He is the guarantor. All authors contributed substantially to the conception and design of the study.

• Competing interests CD has received institutional funding for research from Novartis Pharmaceuticals. James Talks has received travel expenses from Novartis and attended advisory boards for Novartis Pharmaceuticals, Allergan and Bayer. The other authors declare no competing interests.

• Ethics approval Retrospective collection of data from medical records was approved by the research and development department of all three units mentioned.

• Provenance and peer review Not commissioned; externally peer reviewed.

• Data sharing statement Data set available on request from the corresponding author. All available analysis is presented here.