Abstract
The symptoms of COPD frequently affect both patients’ ability to function normally and their quality of life. It is thus important to assess impact of COPD symptoms as well as severity and frequency.
A COPD patient electronic diary (eDiary) has been developed on the basis of qualitative patient interviews. The eDiary was completed by a subset of 209 patients (140, 67% male) in a phase III clinical trial of COPD. They were aged 44 – 86 years (mean 65.3, S.D. 8.7). Items, including both symptoms and bother/difficulty (BD) items, were scored on a 0-10 numeric rating scale. The BD items related to COPD symptoms as a whole, not to specific symptoms. Two morning assessments (since awakening; since last assessment) and one evening assessment were made each day. The mean score of the last seven days of the pre-treatment (baseline) period was analysed.
Correlations between shortness of breath (SB) and BD were > 0.95. Correlations between other symptoms and BD were 0.64 – 0.86. Regression analysis showed that SB was a highly significant (p<0.0001) predictor of BD. Other symptoms added little predictive power once SB had been taken into account. Exploratory factor analysis gave a single factor comprising all eDiary items, including both symptoms and BD. The eDiary showed high internal consistency, with Cronbach’s alpha > 0.95.
The unidimensional nature of the scale indicates that the seven items of the eDiary can be combined to give a single summary measure of COPD.
These results indicate the key importance of shortness of breath for patients with COPD. The very high correlations obtained between this symptom and the ratings of bother and difficulty due to COPD confirm the relevance of this symptom to patients.
- © 2013 ERS