1. Department of Emergency Medicine; Massachusetts General Hospital; Harvard Medical School; Boston MA USA
2. Center for Health Information and Analysis; Commonwealth of Massachusetts; Boston MA USA
3. Office of Survey Research; Center for Health Policy and Research; University of Massachusetts Medical School; Shrewsbury MA USA
4. Departments of Emergency Medicine; Psychiatry; and Quantitative Health Sciences; University of Massachusetts Medical School; Worcester MA USA
5. Butler Hospital; Providence RI USA