[1] Univ Basel, Basel Pharmacoepidemiol Unit, Basel, Switzerland
[2] Creat Ceut Ltd, London, England
[3] Univ Hosp Bristol NHS Fdn Trust, Bristol, Avon, England
[4] Anglia Ruskin Univ, Cambridge, England
[5] Boston Univ, Sch Publ Hlth, Boston Collaborat Drug Surveillance Program, Lexington, MA USA
[6] Univ Hosp Basel, Basel, Switzerland