Airflow limitation among young adults in Europe: A preliminary analysis in a Chronic Airway Diseases Early Stratification (CADSET) collaboration including 109 216 individuals across seven population-based cohorts

Introduction: The extent to which airflow limitation, a key feature of chronic obstructive pulmonary disease (COPD) presenting later in life, is already present in early adulthood is unclear.

Objective: We investigated the prevalence of airflow limitation in young adults across European population-based cohorts.

Methods: Using pre-bronchodilator spirometry measurements from 109,216 individuals aged 20-50 years across seven population-based European cohorts in the CADSET collaboration, we applied two commonly used definitions of airflow limitation: forced expiratory volume in one second [FEV1]/forced vital capacity [FVC] < lower limit of normal (LLN) according to GLI criteria, and FEV1/FVC <0.7. We explored how criteria fulfilment related to sex and ever-smoking.

Results: Prevalence of airflow limitation in young European adults ranged from 3-12% (FEV1/FVC<0·70) and 8-10% (FEV1/FVC<LLN) with increasing age from 20 to 50 in 5-year groups. As expected, at these ages, differences in prevalence of airflow limitation were observed between the FEV1/FVC <0.7 and <LLN criteria. In those aged 20 to 40, the prevalence of airflow limitation according to FEV1/FVC<0.7 was 40% to 80% of that according to FEV1/FVC<LLN. Discordance most affected younger age groups, women, and those with <10 pack-years smoking exposure.

Conclusion: Airflow limitation, by either definition, was common among young adults within these European population cohorts; its cause and its role in prior, concurrent, or future airways disease merits further investigation.