1 Olmsted Medical Center, Rochester, Minnesota and Department of Family and Community Health, University of Minnesota, Rochester.
2 Department of Preventive Medicine and Environmental Health, University of Kentucky, Lexington.
3 Pulmonary and Preventive Medicine, Northwestern University Feinberg School of Medicine, Evanston, Illinois and Northwestern Memorial Hospital, Chicago, Illinois.
4 Pulmonary and Critical Care Medicine, University of Nebraska Medical Center, Omaha.
5 Columbia University Medical Center and New York-Presbyterian Hospital, New York, New York.