Soriano JB, Kendrick PJ, Paulson KR et al (2020) Prevalence and attributable health burden of chronic respiratory diseases, 1990–2017: a systematic analysis for the global burden of disease study 2017. Lancet Respir Med 8:585–596. https://doi.org/10.1016/S2213-2600(20)30105-3

Article  Google Scholar 

Ko FW, Chan KP, Hui DS et al (2016) Acute exacerbation of COPD. Respirology 21:1152–1165. https://doi.org/10.1111/resp.12780

Article  PubMed  PubMed Central  Google Scholar 

Soler-Cataluna JJ (2005) Severe acute exacerbations and mortality in patients with chronic obstructive pulmonary disease. Thorax 60:925–931. https://doi.org/10.1136/thx.2005.040527

Article  CAS  PubMed  PubMed Central  Google Scholar 

Dransfield MT, Kunisaki KM, Strand MJ et al (2017) Acute exacerbations and lung function loss in smokers with and without chronic obstructive pulmonary disease. Am J Respir Crit Care Med 195:324–330. https://doi.org/10.1164/rccm.201605-1014OC

Article  PubMed  PubMed Central  Google Scholar 

Hurst JR, Vestbo J, Anzueto A et al (2010) Susceptibility to exacerbation in chronic obstructive pulmonary disease. N Engl J Med 363:1128–1138. https://doi.org/10.1056/NEJMoa0909883

Article  CAS  PubMed  Google Scholar 

Singh D, Agusti A, Anzueto A et al (2019) Global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease: the GOLD science committee report 2019. Eur Respir J 53:1900164. https://doi.org/10.1183/13993003.00164-2019

Article  CAS  PubMed  Google Scholar 

Hurst JR, Han MK, Singh B et al (2022) Prognostic risk factors for moderate-to-severe exacerbations in patients with chronic obstructive pulmonary disease: a systematic literature review. Respir Res 23:213. https://doi.org/10.1186/s12931-022-02123-5

Article  PubMed  PubMed Central  Google Scholar 

Niewoehner DE, Lokhnygina Y, Rice K et al (2007) Risk indexes for exacerbations and hospitalizations due to COPD. Chest 131:20–28. https://doi.org/10.1378/chest.06-1316

Article  PubMed  Google Scholar 

Vedel-Krogh S, Nielsen SF, Lange P et al (2016) Blood eosinophils and exacerbations in chronic obstructive pulmonary disease. The Copenhagen general population study. Am J Respir Crit Care Med 193:965–974. https://doi.org/10.1164/rccm.201509-1869OC

Article  PubMed  Google Scholar 

Han MK, Quibrera PM, Carretta EE et al (2017) Frequency of exacerbations in patients with chronic obstructive pulmonary disease: an analysis of the SPIROMICS cohort. Lancet Respir Med 5:619–626. https://doi.org/10.1016/S2213-2600(17)30207-2

Article  PubMed  PubMed Central  Google Scholar 

Reilev M, Lykkegaard J, Halling A et al (2017) Stability of the frequent COPD exacerbator in the general population: a danish nationwide register-based study. NPJ Prim Care Respir Med. https://doi.org/10.1038/s41533-017-0029-7

Article  PubMed  PubMed Central  Google Scholar 

Farinha I, Gibson PG, McDonald VM, Heaney LG (2025) Treatable traits as a pathway to remission in asthma. J Allergy Clin Immunol Pract 13:1542–1552. https://doi.org/10.1016/j.jaip.2025.05.002

Article  PubMed  Google Scholar 

Xie C, Wang K, Yang K et al (2025) Toward precision medicine in COPD: phenotypes, endotypes, biomarkers, and treatable traits. Respir Res 26:274. https://doi.org/10.1186/s12931-025-03356-w

Article  PubMed  PubMed Central  Google Scholar 

Pascoe S, Locantore N, Dransfield MT et al (2015) Blood eosinophil counts, exacerbations, and response to the addition of inhaled fluticasone furoate to vilanterol in patients with chronic obstructive pulmonary disease: a secondary analysis of data from two parallel randomised controlled trials. Lancet Respir Med 3:435–442. https://doi.org/10.1016/S2213-2600(15)00106-X

Article  CAS  PubMed  Google Scholar 

Kim VL, Coombs NA, Staples KJ et al (2017) Impact and associations of eosinophilic inflammation in COPD: analysis of the AERIS cohort. Eur Respir J 50:1700853. https://doi.org/10.1183/13993003.00853-2017

Article  CAS  PubMed  Google Scholar 

McDonald CF (2017) Eosinophil biology in COPD. N Engl J Med 377:1680–1682. https://doi.org/10.1056/NEJMe1710326

Article  PubMed  Google Scholar 

Brightling CE, Monteiro W, Ward R et al (2000) Sputum eosinophilia and short-term response to prednisolone in chronic obstructive pulmonary disease: a randomised controlled trial. Lancet 356:1480–1485. https://doi.org/10.1016/S0140-6736(00)02872-5

Article  CAS  PubMed  Google Scholar 

Rutgers S, Timens W, Kaufmann H et al (2000) Comparison of induced sputum with bronchial wash, bronchoalveolar lavage and bronchial biopsies in COPD. Eur Respir J 15:109–115. https://doi.org/10.1183/09031936.00.15110900

Article  CAS  PubMed  Google Scholar 

Pignatti P, Visca D, Cherubino F et al (2019) Do blood eosinophils strictly reflect airway inflammation in COPD? Comparison with asthmatic patients. Respir Res 20:145. https://doi.org/10.1186/s12931-019-1111-1

Article  PubMed  PubMed Central  Google Scholar 

Vanetti M, Visca D, Ardesi F et al (2025) Eosinophils in chronic obstructive pulmonary disease. Ther Adv Respir Dis 19:17534666251335800. https://doi.org/10.1177/17534666251335800

Article  PubMed  PubMed Central  Google Scholar 

Venkatesan P (2023) GOLD COPD report: 2023 update. Lancet Respir Med 11:18. https://doi.org/10.1016/S2213-2600(22)00494-5

Article  PubMed  Google Scholar 

Zhu D, Dai H, Zhu H et al (2023) Identification of frequent acute exacerbations phenotype in COPD patients based on imaging and clinical characteristics. Respir Med 209:107150. https://doi.org/10.1016/j.rmed.2023.107150

Article  PubMed  Google Scholar 

Sunjaya A, Poulos L, Reddel H, Jenkins C (2022) Qualitative validation of the modified medical research council (mMRC) dyspnoea scale as a patient-reported measure of breathlessness severity. Respir Med 203:106984. https://doi.org/10.1016/j.rmed.2022.106984

Article  PubMed  Google Scholar 

Gupta N, Pinto L, Benedetti A et al (2016) The COPD assessment test. Chest 150:1069–1079. https://doi.org/10.1016/j.chest.2016.06.016

Article  PubMed  Google Scholar 

Willgoss TG, Goldbart J, Fatoye F, Yohannes AM (2013) The development and validation of the anxiety inventory for respiratory disease. Chest 144:1587–1596. https://doi.org/10.1378/chest.13-0168

Article  PubMed  Google Scholar 

Bischof AY, Cordier J, Vogel J, Geissler A (2024) Medication adherence halves COPD patients’ hospitalization risk – evidence from swiss health insurance data. NPJ Prim Care Respir Med 34:1. https://doi.org/10.1038/s41533-024-00361-2

Article  PubMed  PubMed Central  Google Scholar 

Wen X, Deng Z, Peng J et al (2023) Characteristics of inflammatory phenotypes in patients with chronic obstructive pulmonary disease: a cross-sectional study. BMJ Open Respir Res 10:e001454. https://doi.org/10.1136/bmjresp-2022-001454

Article  PubMed  PubMed Central  Google Scholar 

Beech A, Singh D (2022) Sputum neutrophil counts in healthy subjects: relationship with age. ERJ Open Res 8:246–2022. https://doi.org/10.1183/23120541.00246-2022

Article  Google Scholar 

Djukanović R, Sterk PJ, Fahy JV, Hargreave FE (2002) Standardised methodology of sputum induction and processing. Eur Respir J 20:1–2. https://doi.org/10.1183/09031936.02.00000102

Article  Google Scholar 

Ouaalaya EH, Falque L, Dupis JM et al (2020) Susceptibility to frequent exacerbation in COPD patients: impact of the exacerbations history, vaccinations and comorbidities? Respir Med 169:106018. https://doi.org/10.1016/j.rmed.2020.106018

Article  PubMed