1. 1Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California.
2. 2Department of Health Care Policy, Harvard Medical School, Boston, Massachusetts; Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts; and National Bureau of Economic Research, Cambridge, Massachusetts.
3. 3Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California.
4. 4Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California.