1. Division of Epidemiology, Office of Pharmacovigilance and Epidemiology, Office of Surveillance and Epidemiology, Center for Drug Evaluation and Research Food and Drug Administration Silver Spring Maryland USA
2. Harvard Medical School Department of Population Medicine Harvard Pilgrim Healthcare Institute Boston Massachusetts USA
3. Division of Pharmacovigilance, Office of Pharmacovigilance and Epidemiology, Office of Surveillance and Epidemiology, Center for Drug Evaluation and Research Food and Drug Administration Silver Spring Maryland USA
4. Division of Biometrics VII, Office of Biostatistics, Center for Drug Evaluation and Research Food and Drug Administration Silver Spring Maryland USA