COPD in never-smokers: risk factors, symptoms, and biomarkers. A follow-up of subjects from the population-based Swedish Cardiopulmonary Bioimage Study (SCAPIS)

<bold>Background:</bold> COPD in never-smokers is common and might have other clinical features than smoking-associated COPD. <bold>Aim:</bold> To investigate risk factors, symptoms, and biomarkers in never-smokers with COPD. <bold>Methods:</bold> We used the SCAPIS cohort to identify a sub-cohort of never-smokers with COPD (n=154), defined as having: FEV₁/FVC<0.70 and FEV₁/FVC<LLN (z-score<-1.64) and FEV₁ 50-100% of predicted value. Sex- and age-matched controls were also recruited: never-smokers with normal lung function (n=281), smokers with normal lung function (n=97), ex-smokers with COPD (n=103) and smokers with COPD (n=55). Spirometry with reversibility testing, fractional exhaled nitric oxide (FeNO) and blood cell differential counts were analysed, as well as data on respiratory symptoms, health status and medical history. <bold>Results:</bold> Never-smokers with COPD had more self-reported asthma (40 vs 12%), IgE sensitization for common airborne allergens (43 vs 30%), higher mean FeNO levels (22 vs 19 ppb) and higher blood eosinophil numbers (0.15 vs 0.13 x 10⁹/L) than never-smokers without COPD. All three groups with COPD and current smokers with normal lung function reported a higher prevalence of respiratory symptoms (wheeze, productive cough), and had lower health status (CAT, SGRQ) than the never-smokers with normal lung function. <bold>Conclusion:</bold> Never-smokers with COPD had decreased health status and features of asthma with higher FeNO and blood eosinophil numbers and were more often allergically sensitized than never-smokers with normal lung function. Our findings emphasise the need for personalised care in COPD and further research into never-smoking related COPD.