Footnotes

• Contributors PAB: conceptualised and designed the study, drafted the initial manuscript and approved the final manuscript as submitted. LFI, BS, DG, KAH, MS and ML: collected the data, critically reviewed the manuscript and approved the final manuscript as submitted. DB: conceptualised the study, critically reviewed the manuscript and approved the final manuscript as submitted.

• Competing interests None.

• Ethics approval RCH Human Research Ethics Committee.

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