Emphysema Phenotype and 1‑Year Readmission Risk After Acute Exacerbation of COPD: A Real-World Study Using Propensity Score-Based Methods

Background: The association between emphysema phenotype and readmission risk after acute exacerbation of chronic obstructive pulmonary disease (AECOPD) remains unclear. This real‑world study evaluated this association with rigorous confounding control. Methods: This retrospective cohort study included patients hospitalized for AECOPD (2023). Emphysema was diagnosed by chest CT. The outcome was 1‑year acute exacerbation‑related readmission. Propensity score matching (PSM), multiple-weighting methods, doubly robust analysis, Schoenfeld residuals test, Kaplan‑Meier curves, and subgroup analyses were used. Results: Among 875 patients, PSM yielded 171 matched pairs. Emphysema was associated with higher readmission risk in adjusted analysis (HR=1.64, 95% CI:1.17– 2.32, p=0.005), and after PSM (HR=1.81, 95% CI:1.22– 2.68, p=0.003). Results were consistent across all weighting methods. The Schoenfeld test satisfied the proportional hazards assumption. Kaplan‑Meier curves showed significantly lower readmission‑free survival in the emphysema group. Subgroup analyses revealed a stronger association in patients not using inhaled corticosteroids. Conclusion: Emphysema was associated with a higher risk of 1‑year readmission after AECOPD. The emphysema phenotype may aid risk stratification and guide individualized therapy, though these findings should be interpreted cautiously. Keywords: AECOPD, emphysema, readmission, propensity score matching