Department of Medicine, University of Verona, 37129 Verona, Italy. Nephrology and Dialysis Unit, Pederzoli Hospital, 37019 Verona, Italy. Nephrology Unit, Ente Ospedaliero Cantonale, 6900 Lugano, Switzerland. Rheumatology Unit, Department of Medical Sciences, University of Ferrara and St. Anna University-Hospital, 44124 Ferrara, Italy. Nephrology, Dialysis and Renal Transplant Unit, IRCCS-Azienda Ospedaliero-Universitaria di Bologna, 40126 Bologna, Italy. Department of Internal Medicine, University of Genoa, 16132 Genoa, Italy. Clinica Nefrologica, Dialisi, Trapianto, IRCCS Ospedale Policlinico San Martino, 16142 Genoa, Italy. Nephrology and Dialysis Unit, Department of Health Sciences, "Magna Graecia" University, 88100 Catanzaro, Italy. Department of Public Health, University Federico II, 80100 Napoli, Italy. Nephrology and Dialysis Unit, St. Anna University-Hospital, 44124 Ferrara, Italy.