Perception of circadian variation of symptoms in Chinese patients with chronic obstructive pulmonary disease

Background: Although, the variable pattern of asthmatic symptoms is well recognized, little is known about the respiratory symptoms variability in patients of chronic obstructive pulmonary disease (COPD). The present study evaluated the variability of the respiratory symptoms in a day and their influence on the daily activities in a cohort of Chinese COPD patients. Methods: An observational cross-sectional study was conducted in 11 medical centers of China. Participants were outpatient >= 40 years old with stable COPD, post-bronchodilator forced expiratory volume in 1 second (FEV1) <80% predicted. Overall, data of 1,032 eligible patients were valid for final analysis. Results: Mean post bronchodilator FEV1 (predicted %) was 46.5%. Cough, expectoration and dyspnea were the most commonly observed symptoms (73.6%, 68.8% and 61.4%, respectively). Daily symptom variability was experienced by 50.2% of symptomatic patients. The wake up time in the morning was the worst and the most troublesome time during the day (39.3%), followed by the nighttime (21.3%). The morning activities were most affected by COPD symptoms. Multivariate analyses revealed that COPD assessment test (CAT) scores was the only factor correlated with patients' symptom variability [odds ratio (OR) =0.463, P<0.0001]. Conclusions: Patient-perceived symptoms vary during the day in Chinese COPD patients. They experience the greatest increase in respiratory symptoms early in the morning. This variation should be considered as a potential new target in the long-term COPD management.