[A three years longitudinal follow-up study of pulmonary function changes in patients with chronic obstructive...

To investigate the characteristics and the risk factors of pulmonary function in patients with chronic obstructive pulmonary disease (COPD) for a 3 year follow-up.

Subjects diagnosed as COPD were followed up for 3 years in the Management Center of Chronic Respiratory Disease at XINQIAO Hospital from September 2009 to June 2012.This was a retrospective study. Parameters related to respiratory function mainly first second forced expiratory volume (FEV1), COPD assessment test (CAT), 6 minutes walking distance (6MWD) and acute exacerbation were recorded during follow-up.

Although the majority of patients were treated with drugs such as inhaled corticosteroid combined with long-term bronchial dilatation during the three years, FEV1 decreased progressively. The average annual decline of FEV1 was(31.80±61.99)ml, translating into a mean annual decline of(3.74±6.18)%. However, there were significant differences in changes of FEV1. Approximately, FEV1 in 78.3% (47/60) patients decreased, only 21.7%(13/60) patients kept stable FEV1. There was a correlation between decrease of FEV1, FEV1%predicted and the exacerbation (r=0.298, 0.361, 0.273; P<0.05). Logistic regression showed that the positive bronchodilator reversibility and the initial FEV1 were the independent factors associated with significant changes in FEV1 (respectively, OR=5.54, 95%CI 1.55-19.73; OR=8.28, 95%CI 1.42-48.32).

The changes of pulmonary function in patients with COPD are heterogeneous, although most patients are treated in a standard way. Nearly 80% patients still represent deterioration of pulmonary function. Decline of FEV1 is closely related to the initial pulmonary function and bronchodilator reversibility.