[1] Merck & Co Inc, Dept Pharmacoepidemiol, Kenilworth, NJ 07033 USA
[2] Merck & Co Inc, Dept Clin Safety & Risk Management, Kenilworth, NJ USA
[3] Pfizer Inc, Safety Surveillance & Risk Management, Groton, CT 06340 USA
[4] Pfizer Inc, Safety Surveillance & Risk Management, Sandwich, Kent, England
[5] Merck & Co Inc, Dept Global Clin Dev, Kenilworth, NJ USA
[6] Univ Maryland, Sch Pharm, Pharmaceut Hlth Serv Res, Baltimore, MD 21201 USA