1. Center for Policy, Outcomes and Prevention, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA
2. Department of Anesthesiology and Critical Care Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA 19146, USA
3. Quantitative Sciences Unit, Department of Pediatrics, Stanford University, Stanford, CA 94305, USA
4. Center for Health Policy, Freeman-Spogli Institute for International Studies, Stanford University, Stanford, CA 94305, USA