1. Johns Hopkins Surgery Center for Outcomes Research, Department of Surgery, Johns Hopkins School of Medicine, Baltimore, MD, USA
2. Department of Surgery, Unaizah College of Medicine, Qassim University, Buraydah, Saudi Arabia
3. Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
4. Department of Surgery, University of Colorado Hospital, Aurora, CO, USA
5. Department of Surgery, University of Virginia, School of Medicine, Charlottesville, VA, USA