1. Department of Epidemiology; Harvard School of Public Health; Boston MA USA
2. Division of Pharmacoepidemiology and Pharmacoeconomics; Brigham and Women's Hospital; Boston MA USA
3. Duke Clinical Research Institute and Department of Medicine; Duke University School of Medicine; NC USA
4. Cardiovascular Epidemiology Research Unit; Beth Israel Deaconess Medical Center; Boston MA USA
5. Department of Anesthesiology, Pharmacology & Therapeutics, Faculty of Medicine; University of British Columbia; Vancouver BC Canada