The variability of respiratory symptoms and associated factors in COPD

Few studies have investigated the variability of COPD-related symptoms or factors related to symptom variability. This observational, prospective, multicentre study was conducted to describe the number and intensity of morning and night-time respiratory symptoms and their variability over one week using the Night-time and Early Morning Symptoms of COPD Instruments (NiSCI and EMSCI) to evaluate stable COPD patients. Logistic regression analyses were performed to investigate factors associated with symptom variability. A total of 2669 patients were evaluated (mean age, 67.7 years; 80.9% men; mean FEV1 50.6%). Of these, 48% reported night-time symptoms and 71% reported morning symptoms. Of the 2293 patients who completed the NiSCI and EMSCI, 90% showed variability in either symptom number (89.6%) or symptom intensity (15.8%). More severe dyspnoea, more exacerbations during the previous year and the exacerbator or mixed COPD-asthma phenotypes were associated with variability in symptom number or intensity. Anxiety was significantly associated with variability in symptom number and intensity. Most COPD patients showed symptom variability over a weeklong period, especially in terms of symptom number. Several COPD-related factors, mainly factors related to more severe disease and more frequent exacerbations, were associated with increased symptom variability.