Daily symptom variability refers to the fluctuation of chronic obstructive pulmonary disease (COPD) symptoms over the day. Although most clinicians can describe the day-to-day variation in symptoms experienced by patients with COPD, little has been done to quantify the variability. This review aims to synthesize evidence of daily symptom variability among patients with stable COPD. Of the 325 potentially relevant articles that were retrieved, 11 observational articles were finally included in the review. Patients with stable COPD commonly experience daily symptom variability, with morning being the most troublesome time of day, followed by night. Morning symptoms had a significant effect on morning routines or daily activities, and night-time symptoms affected the sleep quality of patients. In comparison with patients without symptom variability, patients with morning/night-time symptoms or symptom variability exhibited poorer health status as well as greater disease severity and incidence of exacerbation.
Keywords: chronic obstructive pulmonary disease; stable COPD; symptom variability.