Footnotes

• Contributors SvdS, DC and GM initiated and designed the study with RdH. SvdS collected the data. Data analysis was performed by SvdS, RdH and GM. SvdS drafted the first version of the manuscript. Data interpretation and writing of the manuscript was performed by all authors.

• Funding Academic Medical Center Graduate School PhD stipend for SvdSalm.

• Competing interests None declared.

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