Longitudinal impairment of lung function in school-age children with extremely low birth weights

Abstract

Objectives: To assess lung function and long-term respiratory outcomes in extremely low birth weight (ELBW) survivors.

Working hypothesis: ELBW, especially with respiratory complications in the neonatal period, affects lung function at a later age.

Study design: Longitudinal retrospective study.

Patient-subject selection: Lung function was evaluated in 89 ELBW survivors (at ages 8 and 12) with or without a history of bronchopulmonary dysplasia (BPD) or a bubbly/cystic lung appearance in the neonatal period.

Methodology: FVC, FEV₁ , FEF₅₀ , and FEF₇₅ were measured using spirometry. Two-way repeated-measures ANOVA was used to compare lung function and deterioration time course from 8 to 12 years of age.

Results: Lung function variables were significantly and positively correlated between 8 and 12 years: %FVC (R² = 0.558), %FEV₁ (R² = 0.539), %FEF₅₀ (R² = 0.412), and %FEF₇₅ (R² = 0.429). Lung function values were lower than Japanese reference values, especially in children with a history of severe BPD or a bubbly/cystic appearance. %FEV₁ and FEV₁ /FVC ratio worsened from 8 to 12 years of age: 83.0 ± 17.0% versus 76.6 ± 17.8% (mean difference, 95%CI: -6.43, -9.10 to -3.75) and 84.0 ± 10.1% versus 78.2 ± 13.4% (mean difference, 95%CI: -5.82, -8.56 to -3.08), regardless of whether or not there was a history of neonatal respiratory disease.

Conclusions: In ELBW survivors, the obstructive pattern of lung function impairment deteriorated from 8 to 12 years of age, independent of the presence of severe BPD or bubbly/cystic appearance in the neonatal period.

Keywords: bronchopulmonary dysplasia; chronic lung disease; chronic obstructive pulmonary disease; extremely preterm infant; spirometry.