¹Institute for Healthcare Policy & Innovation, Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA

²Creative Director & Editorial Board, Annals of Surgery, Philadelphia, Pennsylvania, USA

Correspondence: Andrew M. Ibrahim MD, MSc, Institute for Healthcare Policy & Innovation, University of Michigan, 2800 Plymouth Avenue Building 10—G016, Ann Arbor, Michigan 48109-2800, USA. E-mail: iandrew@umich.edu

published online 19 September 2017

SUPPLEMENTARY MATERIAL is linked to the online version of the paper at http://www.nature.com/ajg