1. Department of Population Medicine; Harvard Medical School and Harvard Pilgrim Health Care Institute; Boston MA USA
2. Department of Epidemiology; College of Public Health; University of Iowa; Iowa City IA USA
3. Duke Clinical Research Institute and Department of Medicine; Duke University School of Medicine; Durham NC USA
4. Center for Clinical Epidemiology and Biostatistics; Perelman School of Medicine; University of Pennsylvania; Philadelphia PA USA
5. Biostatistics Unit; Group Health Research Institute; Seattle WA USA
6. Office of Medical Policy, Center for Drug Evaluation and Research; Food and Drug Administration; Silver Spring MD USA
7. Division of Pharmacoepidemiology and Pharmacoeconomics; Brigham and Women's Hospital and Harvard Medical School; Boston MA USA
8. Division of General Internal Medicine, Department of Medicine; Perelman School of Medicine, University of Pennsylvania; Philadelphia PA USA