Impaired lung function and bronchodilator responsiveness in former very preterm infants at preschool age: associated factors and clinical implications.

Background: Preterm birth adversely affects pulmonary development. This study aimed to describe lung function and bronchodilator responsiveness in preschool-aged children born very preterm and to explore perinatal and postnatal factors associated with abnormal spirometry. Methods: We conducted a retrospective cohort study including children born between 2016 and 2019 and admitted to Innsbruck Medical University Hospital with a gestational age below 32 weeks or a birth weight below 1,500 grams. At preschool age, spirometry was performed before and after bronchodilator inhalation. Results: In total, 107 former preterm infants were assessed at a median age of 5.1 years (median gestational age 29.9 weeks; median birth weight 1,250 grams). Of those, 93 (86.9%) children successfully completed spirometry. Twenty-nine children (31%) showed abnormal spirometry and demonstrated greater bronchodilator responsiveness compared with those with normal spirometry (median change in forced expiratory volume in one second: 15.0% vs. 4.9%, Conclusion: In this cohort of children born very preterm, persistent abnormalities in expiratory lung function and increased bronchodilator responsiveness were observed at preschool age. Longer duration of invasive ventilation, glucocorticoid therapy, recurrent respiratory infections, and familial atopic predisposition were associated with poorer pulmonary outcomes.