Background: The prevalences of obstructive and restrictive spirometric phenotypes, and their relation to early-life risk factors from childhood to young adulthood remain poorly understood. The aim was to explore these phenotypes and associations with well-known respiratory risk factors across ages and populations in European cohorts.
Methods: We studied 49 334 participants from 14 population-based cohorts in different age groups (≤10, >10-15, >15-20, >20-25 years, and overall, 5-25 years). The obstructive phenotype was defined as forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) z-score less than the lower limit of normal (LLN), whereas the restrictive phenotype was defined as FEV1/FVC z-score ≥LLN, and FVC z-score <LLN.
Results: The prevalence of obstructive and restrictive phenotypes varied from 3.2-10.9% and 1.8-7.7%, respectively, without clear age trends. A diagnosis of asthma (adjusted odds ratio (aOR=2.55, 95% CI 2.14-3.04), preterm birth (aOR=1.84, 1.27-2.66), maternal smoking during pregnancy (aOR=1.16, 95% CI 1.01-1.35) and family history of asthma (aOR=1.44, 95% CI 1.25-1.66) were associated with a higher prevalence of obstructive, but not restrictive, phenotype across ages (5-25 years). A higher current body mass index (BMI was more often observed in those with the obstructive phenotype but less in those with the restrictive phenotype (aOR=1.05, 95% CI 1.03-1.06 and aOR=0.81, 95% CI 0.78-0.85, per kg·m-2 increase in BMI, respectively). Current smoking was associated with the obstructive phenotype in participants older than 10 years (aOR=1.24, 95% CI 1.05-1.46).
Conclusion: Obstructive and restrictive phenotypes were found to be relatively prevalent during childhood, which supports the early origins concept. Several well-known respiratory risk factors were associated with the obstructive phenotype, whereas only low BMI was associated with the restrictive phenotype, suggesting different underlying pathobiology of these two phenotypes.
Copyright ©The authors 2021.