1. Peritoneal Dialysis Unit, 1st Department of Medicine, AHEPA Hospital, Aristotle University of Thessaloniki , Thessaloniki , Greece
2. Peritoneal Dialysis Unit, General Hospital of Komotini , Komotini , Greece
3. Department of Nephrology, University Hospital of Ioannina , Ioannina , Greece
4. Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki , Thessaloniki , Greece