1. Department of Epidemiology and
2. Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA;
3. Division of Hematology, Oncology and Blood & Marrow Transplantation, Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, IA;
4. Office of Biostatistics and Epidemiology, Center for Biologics Evaluation & Research, US Food and Drug Administration, Silver Spring, MD;
5. Population Research Core, Holden Comprehensive Cancer Center, University of Iowa Hospitals and Clinics, Iowa City, IA; and
6. Division of Research, Kaiser Permanente Northern California, Oakland, CA