[1] Inst Salud Carlos III, Natl Ctr Epidemiol, Madrid 28029, Spain
[2] Univ Alcala, Hosp Ramon y Cajal, Madrid, Spain
[3] Univ Miguel Hernandez, Hosp Univ Elche, Alicante, Spain
[4] Hosp Donosita, San Sebastian, Spain
[5] Hosp Univ Virgen Rocio, Seville, Spain
[6] Univ San Cecilio, Hosp Clin, Granada, Spain
[7] Hosp Univ Canarias, Tenerife, Spain
[8] Hosp La Fe, E-46009 Valencia, Spain
[9] Hosp San Pedro, Logrono, Spain
[10] Univ Rovira & Virgili, Hosp Univ Joan XXIII, Tarragona, Spain
[11] Ctr Salud Publ, Alicante, Spain
[12] Univ Rey Juan Carlos 1, Madrid, Spain