School-age lung function after preterm birth: early-life determinants in a paediatric pulmonology cohort with comparison with NHANES.

Abstract

Lung-function outcomes among preterm-born children referred for pulmonology care are highly heterogeneous, and early determinants remain incompletely defined. We aimed to identify early-life factors associated with school-age lung function after preterm birth and to examine whether school-age spirometry patterns relate to subsequent lung-function trajectories. Early-life analyses (n=511) examined predictors of forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC) z-scores at ages 6-8 years using multivariable regression. Spirometry-based phenotypes included prematurity-associated preserved-ratio impaired spirometry (pPRISm), prematurity-associated obstructive lung disease (POLD) and prematurity-associated dysanapsis. Longitudinal mixed-effects models assessed lung-function trajectories from ages 8 to 21 years. Parallel analyses were conducted in the National Health and Nutrition Examination Survey (NHANES). Lower weight-for-height at 4 years was non-linearly associated with both FEV₁ and FVC at school age. Invasive ventilation in the first year of life was associated with lower FEV₁ (β -0.62, 95% CI -0.96 to -0.28) and FVC (β -0.54, 95% CI -0.92 to -0.18). In exploratory analyses, pPRISm was inversely associated with neighbourhood income (risk ratio (RR) 0.63 per SD increase, 95% CI 0.46 to 0.88), and POLD was associated with invasive ventilation (RR 8.07, 95% CI 3.33 to 19.5). Similar subtypes and associations were observed in NHANES. School-age pPRISm was associated with progressive FEV₁ z-score decline (age x pPRISm β -0.08 SD/year, 95% CI -0.15 to -0.02), while POLD was associated with improving FVC z-score (age x POLD β 0.13 SD/year, 95% CI 0.07 to 0.20). Early-childhood growth, neonatal respiratory exposures and school-age spirometry patterns help stratify long-term pulmonary risk among preterm-born children referred for pulmonary care.