Background: Type-2 inflammatory biomarkers blood eosinophils (BE) and fraction of exhaled nitric oxide (FeNO) have been associated with asthma morbidity. We tested the hypothesis that type-2 inflammation is associated with accelerated lung function decline in chronic airway disease in the general population.

Methods: We included 15 605 adults from the Copenhagen General Population Study and investigated the relationship between BE and FeNO with decline in forced expiratory volume in 1 second (FEV1) over 10 years. Information on BE was available in all, whereas FeNO was available in 2853 individuals. Individuals were grouped according to presence of chronic airway disease, including asthma, chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap. Analyses were adjusted for age, sex, height, smoking, and airway medication.

Results: Elevated BE and FeNO were associated with accelerated FEV1 decline. Adjusted annual FEV1 decline was 25 mL in those with BE <150 cells/?L, 26 mL in BE 150-299 cells/?L, and 29 mL in BE ?300 cells/?L. Annual FEV1 decline was 19 mL in FeNO <20 ppb and 24 mL in FeNO ?20 ppb. Annual FEV1 decline was 18 mL in BE <300 cells/?L and FeNO <20 ppb, 22 mL in BE ?300 cells/?L or FeNO ?20 ppb, and 27 mL in BE ?300 cells/?L and FeNO ?20 ppb. Individuals with chronic airway disease experienced a higher FEV1 decline than those without, but the association between BE and FeNO with FEV1 decline was similar.

Conclusions: Increased type-2 inflammation was associated with accelerated FEV1 decline in those with and without chronic airway disease in the general population.

Funding: Sanofi Genzyme and Capital Region of Denmark.