[1] McMaster Univ, Dept Clin Epidemiol, Hamilton, ON L8S 4L8, Canada
[2] McMaster Univ, Med, Hamilton, ON, Canada
[3] McMaster Univ, Clin Epidemiol & Biostat, Hamilton, ON, Canada
[4] Azienda Osped Policlin Careggi, Florence, Italy
[5] Van Creveld Clin, Utrecth, Netherlands
[6] Univ Sheffield, Sheffield, S Yorkshire, England
[7] Univ Lille, Lille, France
[8] Unviers Izmir, Izmir, Turkey
[9] Univ Berlin, Berlin, Germany
[10] Univ Paris, F-75252 Paris, France
[11] Bayer, Pittsburgh, PA USA
[12] Policlin Univ, Parma, Italy
[13] Baxter Healthcare, Los Angeles, CA USA
[14] Policlin Univ, Parma, Italy
[15] Univ Warsaw, Warsaw, Poland
[16] Univ Padua Polyclin, Padua, Italy