Symptoms and impact of COPD assessed by an electronic diary in patients with moderate-to-severe COPD: psychometric results from the SHINE study

BACKGROUND Symptoms, particularly dyspnea, and activity limitation, have an impact on the health status and the ability to function normally in patients with chronic obstructive pulmonary disease (COPD). METHODS To develop an electronic patient diary (eDiary), qualitative patient interviews were conducted from 2009 to 2010 to identify relevant symptoms and degree of bother due to symptoms. The eDiary was completed by a subset of 209 patients with moderate-to-severe COPD in the 26-week QVA149 SHINE study. Two morning assessments (since awakening and since the last assessment) and one evening assessment were made each day. Assessments covered five symptoms ("shortness of breath," "phlegm/mucus," "chest tightness," "wheezing," and "coughing") and two impact items ("bothered by COPD" and "difficulty with activities") and were scored on a 10-point numeric scale. RESULTS Patient compliance with the eDiary was 90.4% at baseline and 81.3% at week 26. Correlations between shortness of breath and impact items were >0.95. Regression analysis showed that shortness of breath was a highly significant (P<0.0001) predictor of impact items. Exploratory factor analysis gave a single factor comprising all eDiary items, including both symptoms and impact items. Shortness of breath, the total score (including five symptoms and two impact items), and the five-item symptom score from the eDiary performed well, with good consistency and reliability. The eDiary showed good sensitivity to change, with a 0.6 points reduction in the symptoms scores (on a 0-10 point scale) representing a meaningful change. CONCLUSION The eDiary was found to be valid, reliable, and responsive. The high correlations obtained between "shortness of breath" and the ratings of "bother" and "difficulty with activities" confirmed the relevance of this symptom in patients with COPD. Future studies will be required to explore further psychometric properties and their ability to differentiate between COPD treatments.