1. Department of Nephrology and Dialysis, St. Andrea Hospital, La Spezia - Italy
2. Department of Nephrology and Dialysis, St. Paolo Hospital, Civitavecchia - Italy
3. Department of Nephrology and Dialysis, St. Giovanni di Dio Hospital, Agrigento - Italy
4. Department of Nephrology and Dialysis, St. Francesco Hospital, Nuoro - Italy
5. Casa Di Cura Nuova Di Decimomannu, Cagliari - Italy
6. Department of Nephrology and Dialysis, L. Parodi Delfino Hospital, Colleferro - Italy