Declarations: The authors declare no conflict of interest.
Abbreviations: AECOPD: acute exacerbations of chronic obstructive pulmonary disease; COPD: chronic obstructive pulmonary disease; DHC: daily hospital costs; GOLD: global initiative for chronic obstructive pulmonary disease; HR: Hazard ratio; Hs-CRP: hypersensitive C-reactive protein; mMRC: Modified Medical Research Council; CNY: Chinese Yuan; DHC: daily hospital costs; LOS: Length of stay; OHC: overall hospital costs; Th2:T-helper cell type 2;
Authors’ contributions: (I) Conception and design: T.W and F.Q.; (II) Administrative support: H.Z. and F.Q.; (III) Provision of study materials or patients: Q.Z, H.Z.; (IV) Collection and assembly of data: Q.Z, H.W, and K.W.; (V) Data analysis and interpretation: Q.Z, and H.W.; (VI) Manuscript writing: Q.Z., and H.W.;; (VII) Final approval of manuscript: All authors; (VIII) Guarantor of the paper: F.Q.; All authors have read and agreed to the published version of the manuscript.
Acknowledgements: We thank Yao Wang, Xu Zhang, and Simeng Qiu for their assistance on data collection.
Availability of data and materials :The datasets during the current study are available from the corresponding author on reasonable request.Consent for publication: Not applicable.
Ethics approval and consent to participate: The study was approved by the ethics community of the Affiliated Hospital of Chengdu University (NO: PJ2018-012-02).