At least one underlying medical condition was documented for 40 (43%) of the 94 children; the most frequent condition was obesity defined as Body Mass Index >90th percentile (n = 12, 30% of all 40 children with predisposing factors), asthma (n = 10, 25%), neurologic disorders (n = 8, 20%), preterm birth, allergic diseases and other chronic diseases (each n = 6, 15%).