1. Division of Pulmonary, Allergy, and Critical Care, Perelman School of Medicine,
2. Leonard Davis Institute of Health Economics,
3. Palliative and Advanced Illness Research Center, Perelman School of Medicine,
4. Department of Statistics, The Wharton School,
5. Center for Emergency Care Policy and Research, Department of Emergency Medicine, Perelman School of Medicine, and
6. Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; and
7. Division of Research, Kaiser Permanente, Oakland, California