Bronchiolitis in infancy is an important risk factor for asthma but not for allergic sensitization at age 6

Abstract

Background: Risk factors for bronchiolitis and for long term respiratory sequelae remain unclear.

Aim: To study the occurrences of asthma and allergic sensitization after bronchiolitis.

Materials: 622 children hospitalized for bronchiolitis (cases) during 9 consecutive seasons and 65 healthy children enrolled in “Piccolipiù” cohort with negative history for bronchiolitis (controls) were followed for 6 years. A structured questionnaire was used to obtain demographic information from all children. Parents were interviewed 5 years after hospitalization to check whether their children experienced recurrent wheezing. At 6 years of age 253 cases and all controls performed prick test.

Results: Cases had lower gestational age (p=0.001), lower birth weight (p=0.016), higher smoking exposure during their first year of life (p<0.0001), less frequently family history for asthma (p=0.007) and less frequently breastfed (p<0.0001) compared to the control group. Asthma at the age of 6 years was more frequent in cases than in controls (21.2% vs 7.7%, p=0.05). Positive prick tests were more frequent in the control group than in the bronchiolitis group (32.8% vs 22.7%, p=0.068). The logistic regression analysis found breastfeeding, gestational age, birth weight and smoking exposure as risk factors for bronchiolitis; breastfeeding, family history for asthma and bronchiolitis were risk factors for asthma at 6 years.

Conclusions: Environmental factors seems to have an important role in bronchiolitis. Bronchiolitis is a risk factor or asthma but not for allergic sensitization.