Annual decline in forced expiratory volume and airway inflammatory cells and mediators in a general population-based sample

BACKGROUND: Few studies have examined the relationships between sputum inflammatory markers and subsequent annual decline in forced expiratory volume in 1 s (dFEV(1)). This study investigated whether indices of airway inflammation are predictors of dFEV(1) in a general population-based sample. METHODS: The study, conducted from 2003 to 2005, included 120 healthy Norwegian subjects aged 40 to 70 years old. At baseline, the participants completed a self-administered respiratory questionnaire and underwent a clinical examination that included spirometry, venous blood sampling, and induced sputum examination. From 2015 to 2016, 62 (52%) participants agreed to a follow-up examination that did not include induced sputum examination. Those with a FEV(1)/forced vital capacity (FVC) ratio < 0.70 underwent a bronchial reversibility test. The levels of cytokines, pro-inflammatory M1 macrophage phenotypes were measured in induced sputum using bead-based multiplex analysis. The associations between cytokine levels and dFEV(1) were then analysed. RESULTS: The mean dFEV(1) was 32.9 ml/year (standard deviation 26.3). We found no associations between dFEV(1) and the baseline indices of sputum inflammation. Seven participants had irreversible airflow limitation at follow-up. They had lower FEV1 and gas diffusion at baseline compared with the remaining subjects. Moreover, two of these individuals had a positive reversibility test and sputum eosinophilia at baseline. CONCLUSIONS: In this cohort of presumably healthy subjects, we found no associations between sputum inflammatory cells or mediators and dFEV(1) during 10 years of follow-up. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12890-018-0765-7) contains supplementary material, which is available to authorized users.