[1] HU Marques Valdecilla, Dept Nephrol, Santander 39008, Spain
[2] H Clin San Carlos, Madrid, Spain
[3] Hosp Gen Gregorio Maranon, Madrid, Spain
[4] Hosp La Fe, E-46009 Valencia, Spain
[5] Fdn Jimenez Diaz, E-28040 Madrid, Spain
[6] H Cruces, Baracaldo, Spain
[7] Univ Navarra Clin, Pamplona, Spain
[8] Hosp 12 Octubre, E-28041 Madrid, Spain
[9] Hosp Clin Barcelona, Barcelona, Spain
[10] Hosp Son Dureta, Palma de Mallorca, Spain
[11] HS Clin Santiago, Santiago De Compostela, Spain
[12] Hosp Ramon & Cajal, E-28034 Madrid, Spain
[13] Fdn Puigvert, Barcelona, Spain
[14] Hosp Gen Valle Hebron, Barcelona, Spain