Footnotes

• Twitter @Carol_Stephens_

• Contributors LG, NM, OO'M and MJO'L were responsible for planning the design of this study. CS and ZC were responsible for data collection. CS analysed the collected data and completed the first draft of the manuscript. All authors contributed to further edits and proofreading of the 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.

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