[1] Univ Athens, Sch Med, Dept Pediat 1, Pediat Pulmonol Unit, GR-11527 Athens, Greece
[2] Aghia Sophia Childrens Hosp, Athens, Greece
[3] Tufts Univ, Sch Med, Tufts Med Ctr, Ctr Clin Evidence Synth,Inst Clin Res & Hlth Poli, Boston, MA 02111 USA
[4] Univ Thessaly, Sch Med, Dept Biomath, Larisa, Greece