Footnotes

• Contributors PS and VF conceived the idea of the study. MN and PS designed the study. MN led the coordination of data collection, analysis and writing the first draft of the manuscript. CH, AA, SG-O and MA collected the data. All authors edited the manuscript and critically assessed and approved its final form.

• 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.

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