Footnotes

• Contributors SB designed the study, acquired, analysed and interpreted data, and drafted the manuscript. J-PS analysed and interpreted data, and revised the manuscript for important intellectual content. GG and FHS acquired and interpreted data, and revised the manuscript for important intellectual content. AC designed the study, interpreted data and revised the manuscript for important intellectual content. All authors have approved the final submitted version.

• Competing interests SB, J-PS, GG, FHS and AC declare that they have no competing interests in the research.

• Ethics approval Ethikkommission am Universitätsklinikum Essen.

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