Footnotes

• Contributors All the authors made contributions in the acquisition, analysis and interpretation of data. In addition, they revised it critically for important intellectual content and gave their final approval of the version published.LMAG additionally conceived and designed the study and drafted 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.

• Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.

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