Author Contribution
Concept and design: Becker, Gross, Gamp, HunzikerAcquisition, analysis, or interpretation of data: Becker, Gross, HunzikerDrafting of the manuscript: Becker, Gross, HunzikerCritical revision of the manuscript for important intellectual content: all authorsStatistical analysis: Becker, Gross, HunzikerAdministrative, technical, or material support: Schaefert, Bassetti, Leuppi, Schuetz, HunzikerSupervision: Hunziker