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

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), FEV1%pred ( P =0.002), maximal mid-expiratory flow (MMEF25-75%pred ) ( P =0.003), and ratio of carbon monoxide diffusion capacity to alveolar ventilation (DLCO/VA) ( P =0.03) and higher resonant frequency (Fres ; 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 MEDleft 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.