Background
Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have a major impact on patients and healthcare systems across the globe. Estimates on mortality and readmission rates are characterized by great heterogeneity. The present study aimed to provide precise estimates on in-hospital mortality, post-discharge mortality and hospital readmission rates after AECOPD-related hospitalization by pooling results from existing cohort studies using an individual patient data meta-analysis (IPDMA) design. 

Methods
A systematic review was conducted in accordance with the PRISMA-IPD guidelines identifying studies that reported in-hospital mortality, post-discharge mortality and hospital readmission rates of patients during and/or following AECOPD-related hospitalization. Stratified and pooled analyses were performed on IPD using a harmonized protocol. Factors associated with these outcomes were explored using univariate and multivariate age and sex adjusted Cox proportional hazards regressions. 

Results
IPD of 65945 patients with COPD from 47 studies across the globe has been collected, received and analyzed. The in-hospital mortality rate was 6.2%, the post-discharge mortality rate was 15.2% and the hospital readmission rate was 32.8%. The median post-discharge follow-up time was 365 days. The strongest predictor of in-hospital mortality was use of non-invasive mechanical ventilation (NIMV) (HR 4.09, p<0.001). A history of ≥2 AECOPD-related hospitalizations in the past year revealed to be the strongest predictor of both post-discharge mortality (HR 2.09, p<0.001) and hospital readmission (HR 2.50, p<0.001).

Conclusion
The current IPDMA highlights the poor prognosis both during and after AECOPD-related hospitalization in patients with COPD across the globe. There is an urgent need to develop effective severe AECOPD prevention strategies.