Risk factors predict frequent hospitalization in patients with acute exacerbation of COPD

Abstract

Purpose

COPD is a heterogeneous disease, and the available prognostic indexes are therefore limited. This study aimed to identify the factors associated with acute exacerbation leading to hospitalization.

Patients and methods

This was a retrospective study of consecutive patients with COPD (meeting the Global Initiative for Chronic Obstructive Lung Disease [GOLD] diagnostic criteria) hospitalized at the Ninth Hospital of Xi’an Affiliated Hospital of Xi’an Jiaotong University between October 2014 and September 2016. During follow-up after first hospitalization, the patients who had been rehospitalized within 1 year for acute exacerbation were grouped into the frequent exacerbation (FE) group, while the others were grouped into the infrequent exacerbation (IE) group. The baseline demographic, clinical, laboratory, pulmonary function, and imaging data were compared between the two groups.

Results

Compared with the IE group, the FE group had lower forced expiratory volume in 1 second (FEV₁)/forced vital capacity (FVC) (P=0.005), FEV_1%pred (P=0.002), maximal mid-expiratory flow (MMEF_25–75%pred) (P=0.003), and ratio of carbon monoxide diffusion capacity to alveolar ventilation (DLCO/VA) (P=0.03) and higher resonant frequency (F_res; P=0.04). According to generations of bronchi, the percentage of the wall area (%WA) of lobes was found to be higher in the FE group. Emphysema index (EI), mean emphysema density (MED)_whole and MED_{left lung} in the FE group were significantly worse than in the IE group (P<0.05). Using logistic regression, exacerbation hospitalizations in the past year (odds ratio [OR] 14.4, 95% CI 6.1–34.0, P<0.001) and EI >10% (OR 2.9, 95% CI 1.2–7.1, P=0.02) were independently associated with frequent acute exacerbation of COPD (AECOPD) hospitalization.

Conclusion

Exacerbation hospitalizations in the past year and imaging features of emphysema (EI) were independently associated with FE hospitalization.

Keywords:

• acute exacerbation
• COPD
• pulmonary function test
• frequent hospitalization
• respiratory function tests
• computed tomography

Acknowledgments

This study was supported by the Shaanxi Province Social Development Science and Technology Research Project (Grant No 2016SF-151) and by the Xi’an Science and Technology Project (Grant No 2016045SF/YX01). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Author contributions

XW and ZQM conceived and coordinated the study, designed, performed, and analyzed the experiments, and wrote the paper. NY, JTR, CWJ, JYM, MJS, LBT, and YZG carried out the data collection, data analysis, and revised the paper. YMG designed the study and revised the paper. All the authors reviewed the results and approved the final version of the manuscript. All the authors participated in substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; drafting the paper or revising it critically for important intellectual content; final approval of the version to be published; and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Disclosure

The authors report no conflicts of interest in this work.