1. From the Division of Basic and Clinical Immunology, Department of Medicine, University of California Irvine, Orange, California
2. Department of Allergy, Asthma, and Clinical Immunology, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California
3. Department of Statistics, University of California Irvine, Irvine, California, and
4. Division of Geriatric, Hospital, Palliative and General Internal Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, California