Footnotes

• Twitter @Joanna86992517, @esragbilir, @aStrojnaMD, @agz_eriksson

• Contributors JK-B: study concept, preparation of the draft manuscript, guarantor. EB: study concept, figure preparation, study concept, preparation of the draft manuscript. SN: critical review of the manuscript. AS: critical review of the manuscript. AGE: critical review of the manuscript, project supervision.

• 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.