Footnotes

• Contributors LDD and SB conceived the study with input from DG, FT and EG. SB and FT retrieved and reviewed the medical records. EG and DG analysed and interpreted the data. All authors reviewed and interpreted data. SB drafted the manuscript, which was revised by all authors.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient consent for publication Not required.

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