1 Michigan State University College of Human Medicine, Grand Rapids, MI, U.S.A.
2 Department of Dermatology, University of Illinois at Chicago College of Medicine, Chicago, IL, U.S.A.
3 Department of Dermatology, University of Colorado Anschutz Medical Campus, Aurora, CO, U.S.A.
4 Dermatology Service, U.S. Department of Veterans Affairs, Eastern Colorado Health Care System, 1055 Clermont Street, Box 165, Denver, CO, 80220, U.S.A.
5 Department of Epidemiology, Colorado School of Public Health, University of Colorado Anschutz Medical Campus, Aurora, CO, U.S.A.