1 Division of Emergency Medicine, Children's Mercy Hospitals, Kansas City, MO, Assistant Professor, Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA. admcneilljohnson@cmh.edu.
2 Associate Professor, Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
3 Professor of Pediatrics and Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA.
4 Associate Professor, Department of Pediatrics, UCLA David Geffen School of Medicine, Los Angeles, CA, USA.