Lung function development after preterm birth in relation to severity of Bronchopulmonary dysplasia

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a strong risk factor for respiratory morbidity in children born preterm. Our aims were to evaluate lung function in adolescents born preterm with and without a history of BPD, and to assess lung function change over time from school age. METHODS: Fifty-one individuals born in Stockholm, Sweden between gestational ages 24 to 31 weeks (23 neonatally diagnosed with respiratory distress syndrome (RDS) but not BPD, and 28 graded as mild (n = 17), moderate (n = 7) or severe (n = 4) BPD) were examined in adolescence (13–17 years of age) using spirometry, impulse oscillometry (IOS), plethysmography, and ergospirometry. Comparison with lung function data from school age (6–8 years of age) was also performed. RESULTS: Adolescents with a history of BPD had lower forced expiratory volume in 1 s (FEV(1)) compared to those without BPD (−0.61 vs.-0.02 z-scores, P < 0.05), with lower FEV(1) values significantly associated with BPD severity (P for trend 0.002). Subjects with severe BPD had higher frequency dependence of resistance, R(5–20), (P < 0.001 vs. non-BPD subjects) which is an IOS indicator of peripheral airway involvement. Between school age and adolescence, FEV(1)/FVC z-scores decreased in all groups and particularly in the severe BPD group (from −1.68 z-scores at 6–8 years to −2.74 z-scores at 13–17 years, p < 0.05 compared to the non-BPD group). CONCLUSIONS: Our results of spirometry and IOS measures in the BPD groups compared to the non-BPD group suggest airway obstruction including involvement of peripheral airways. The longitudinal result of a decrease in FEV(1)/FVC in the group with severe BPD might implicate a route towards chronic airway obstruction in adulthood.