Footnotes

• Contributors CC, OR and FF wrote the manuscript. BB performed the statistical analysis. AD and PM participated in the coordination of the manuscript. All authors read and approved the final manuscript.

• 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 Not required.

• Provenance and peer review Commissioned; internally peer reviewed.