Predictors of lung function in early adulthood: A population-based cohort study.

Background and objective: Lung function reaches a peak/plateau in early adulthood before declining with age. Lower early adult lung function may increase the risk for chronic obstructive pulmonary disease (COPD) in mid-late adult life. Understanding the effects of multiple childhood/adolescent exposures and their potential interactions on plateau lung function would provide insights into the natural history of COPD.

Methods: Longitudinal spirometry data from 688 participants with complete data from a population-based birth cohort (original n = 1037) were used to investigate associations between a wide range of childhood/adolescent exposures and repeated measures of FEV₁, FVC and FEV₁/FVC during the early-adult plateau phase. Generalized estimating equations were used to accommodate the multiple timepoints per participant.

Results: FEV₁ reached a peak/plateau between ages 18 and 26 and FVC from 21 to 32 years, whereas FEV₁/FVC declined throughout early adulthood. Childhood asthma and airway hyperresponsiveness were associated with lower early adult FEV₁ and FEV₁/FVC. Smoking by age 18 was associated with lower FEV₁/FVC. Higher BMI during early adulthood was associated with lower FEV₁ and FVC and lower FEV₁/FVC. Physical activity during adolescence was positively associated with FEV₁ and FEV₁/FVC but this was only statistically significant in men. There was no convincing evidence of interactions between exposures.

Conclusion: Childhood asthma and airway hyperresponsiveness are associated with lower lung function in early adulthood. Interventions targeting these may reduce the risk of COPD in mid-late adult life. Promotion of physical activity during adolescence, prevention of cigarette smoking and maintenance of a healthy body weight in early adulthood are also priorities.