Table 1. Number of patients per center included in statistical analysis.

Center	Number of patients
S. Orsola Malphighi Hospital, Bologna, Italy	119 (45.2%)
University Medical Center Groningen, Groningen, The Netherlands	45 (17.1%)
San Martino University Hospital, Genua, Italy	20 (7.6%)
Regional University Hospital of Patras, Patras, Greece	31 (11.8%)
The Highfield Hospital, Manchester, United Kingdom	19 (7.2%)
S. Maria Hospital, Perugia, Italy	15 (5.7%)
Clinical Center Nis, Nis, Serbia	14 (5.3%)
Total	263