ABSTRACT
PURPOSE: Both under-nutrition and obesity may be associated with severity of viral infection. We investigated the association of obesity with clinical factors and the severity of acute bronchiolitis in infants. METHODS: We reviewed 740 infants younger than 1 year of age who were admitted with the first episode of acute bronchiolitis between 2010 and 2013. Subjects were classified into 3 groups according to the weight-for-length Z-score. RESULTS: Younger age (3.6+/-2.6 months) was more frequent in the obesity group (P<0.001). Infants aged < or =6 months (90%) dominantly included in the obesity group. Logistic regression showed that age (younger than 3 months) was independently associated with the overweight and obesity groups with acute bronchiolitis in infants (odds ratio [OR], 1.77; P=0.001 for overweight; OR, 4.67; P<0.001 for obesity). Moreover, the obesity group was associated with an increased risk of chest retraction, hypoxia, respiratory syncytial virus detection, length of stay (more than 5 days), and need for oxygen supplement. These factors tended to increase from the overweight group toward the obesity group. CONCLUSION: Younger than 3 months of age was a risk factor for developing worse clinical course in overweight and obesity groups with acute bronchiolitis in infants. Careful attention should be paid to the clinical course of younger obese infants with acute bronchiolitis.