[1] IRCCS Fdn Policlin S Matteo, Serv Biometry & Stat, Pavia, Italy
[2] Univ Modena & Reggio Emilia, Dept Cardiol, Policlin Modena, Reggio Emilia, Italy
[3] Clin Sud Luxembourg, Arlon, Belgium
[4] Karolinska Univ Hosp, Stockholm, Sweden
[5] IRCCS Fdn Policlin S Matteo, Ctr Sci Documentat, Pavia, Italy
[6] Aston Univ, Aston Med Sch, Aston Med Res Inst, Birmingham B4 7ET, W Midlands, England