1. Medical Direction, Fresenius Medical Care, Madrid, Spain
2. Department of Nephrology, Hospital del Mar, Barcelona, Spain
3. Department of Nephrology, H. U. Valdecilla, Santander, Spain
4. Department of Nephrology, Hospital General Universitario Gregorio Marañón, Madrid, Spain
5. RedInRen, Instituto de Salud Carlos III, Córdoba, Spain
6. Department of Nephrology, Hospital Universitario Reina Sofía, Córdoba, Spain
7. Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Universidad de Córdoba, Córdoba, Spain
8. Department of Nephrology, Hospital Universitario 12 de Octubre, Madrid, Spain