1. Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, Ohio
2. Geisinger Center for Health Research, Geisinger Health System, Danville, Pennsylvania
3. Boston University School of Medicine and the VA Boston Healthcare System, Boston, Massachusetts
4. Department of Epidemiology and the Department of Medicine, Johns Hopkins University, Baltimore, Maryland
5. Georgetown University School of Medicine and MedStar Research Institute, Hyattsville, Maryland
6. Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
7. Southern Arizona VA Healthcare System and the University of Arizona College of Medicine, Tucson, Arizona
8. Center for Clinical Investigation, Case Western Reserve University, Cleveland, Ohio