Introduction: Bronchiolitis is the leading cause of hospitalization in infants with respiratory distress in the winter. It is most commonly caused by respiratory syncytial virus (RSV). The increased hospitalization rate in premature infants has been quantified but questions remain as to the severity in those born “late-premature”.
Objective: To prospectively assess rates of hospitalization for RSV bronchiolitis for all degrees of prematurity.
Methods: All hospitalized infants (< 1yr) who met the clinical criteria for acute bronchiolitis and had a positive RSV nasal aspirate, were included. Reference birth rates were obtained from a national cohort study. Prematurity was defined as gestational age < 33+6 weeks; late premature: 34-36+6 weeks and term: > 37 weeks with an additional analysis of “extended late premature” defined as 34-37+6 weeks gestation. Pavilizumab was not available for infants born 33 weeks gestation or more.
Results: The percentage of admissions of infants who were born prematurely or at term was not significantly more than in the birth cohort. However, 9.2% and 17.9% were born late preterm and extended late preterm respectively, significantly greater than represented in the reference birth cohort (p<0.001). Length of stay (LOS) in the pediatric ICU was significantly greater for those born late preterm than term babies (11.5 vs 6.6 days).
Conclusions: There is a significant over-representation of babies born 34-36+6 weeks and 34-37+6 among infants hospitalized for acute RSV bronchiolitis. This adds to the growing evidence of increased risk of respiratory disease in the late prematurely born infants.
