[1] Hosp Clin San Carlos, Lab Med Dept, Madrid, Spain
[2] Univ Complutense, Hosp Clin San Carlos, Fac Med, Pediat Dept, Madrid, Spain
[3] Miguel Hernandez Univ, Dept Clin Med, Alicante, Spain
[4] Univ Alfonso X Sabio, Hosp Clin San Carlos, Epidemiol Dept, Madrid, Spain
[5] Univ Complutense, Hosp Clin San Carlos, Fac Med, Internal Med Dept, Madrid, Spain