Premature birth is associated with increased susceptibility to viral infections and chronic airway morbidity. Even moderate and late preterm children may be at risk for short- and long-term respiratory morbidities. Our main goal was to compare the burden of two conditions, severe bronchiolitis and prematurity (early and moderate-late), on asthma development at 6– 9 years.
A retrospective cohort of all preterm (< 37weeks gestational age) and full-term children hospitalized for bronchiolitis, with current age between 6 and 9 years, was created. A second cohort was made up of preterm children, randomly chosen from the hospital’s premature births database, without admission for bronchiolitis. Prevalence and risk factors for asthma were analyzed. Parents completed the International Study of Asthma and Allergies in Childhood (ISAAC) Questionnaire for asthma symptoms for children 6– 7 years. Lung function and aeroallergen sensitization were evaluated.
Of the 480 selected children, 399 could be contacted and agreed to participate: 133 preterm and 114 full-term cases with admission for bronchiolitis and 146 preterm control children without admission for bronchiolitis. The frequency of current asthma at 6– 9 years was higher in preterm cases (27%) compared with full-term-cases (15%) and preterm controls (14%) (p=0.04). Among hospitalized-bronchiolitis children, prematurity (p=0.04), rhinovirus infection (p=0.03), viral coinfection (p=0.04) and paternal asthma (p=0.003) were risk factors for asthma at 6– 9 years. Among premature children, with and without bronchiolitis admission, the risk factors for asthma at 6– 9 years were admission for bronchiolitis (p=0.03) and aeroallergen sensitization (p=0.01). Moderate and late preterm children without admission for bronchiolitis showed a similar prevalence of current asthma than full-term ones previously admitted for bronchiolitis.
Preterm birth is an important early life risk factor for asthma in childhood. Other risk factors, such as severe bronchiolitis, especially by rhinovirus or viral coinfections, are associated with an even higher risk for subsequent asthma.