The quality of life (QOL) scores：St George's dyspnea score (SGRQ score）, modified british medical reserach council（mMRC score) and COPD assessment test (CAT score); lung function test: forced expiratory volume in one second (FEV1）,FEV1% predicted, the ratio of forced expiratory volume in one second and forced vital capacity (FEV1/FVC%); short-acting β2-adrenergic agonist（SABA）use and the incidence of adverse event were monitored throughout the study.