Footnotes

• Twitter Follow David Hewett at @dghewett

• Contributors SS designed the study, led the data acquisition and interpretation, and wrote the manuscript; FM assisted with data collection and study support, KK performed the statistical analysis; ARS provided study support; DGH contributed to study design, data interpretation and manuscript preparation; all authors critically reviewed the manuscript for important intellectual content.

• Competing interests DGH receives consulting fees from Olympus Corporation, Tokyo, Japan.

• Ethics approval The Human Research Ethics Committee of the University of Queensland.

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