Reliability, validity and responsiveness of E-RS:COPD in patients with spirometric asthma-COPD overlap

Respiratory Research

Table 3 Internal consistency and test-retest reliability of E-RS Total and domain scores and wheeze

			Internal consistency	Test-retest reliability
			Day − 1 (N = 328)	Day − 2 to Day − 1^a
	Scale	No. items	Cronbach’s alpha (raw)	Difference in mean (SD) score between days	p-value	ICC (95% CI)
All	RS-Total	11	0.91	0.21	0.2983	0.83 (0.79–0.86)
	RS-Cough and Sputum	4	0.71	0.07	0.2686	0.78 (0.74–0.82)
	RS-Chest Symptoms	2	0.86	0.03	0.6776	0.73 (0.67–0.78)
	RS-Breathlessness	5	0.89	0.10	0.3795	0.80 (0.76–0.84)
	Wheeze	1	–	0.03	0.3411	0.75 (0.70–0.80)
Morning PEF change < 15%	RS-Total	11	–	0.30	0.2492	0.82 (0.77–0.86)
	RS-Cough and Sputum	4	–	0.11	0.1877	0.77 (0.70–0.82)
	RS-Chest Symptoms	2	–	0.04	0.6643	0.72 (0.65–0.78)
	RS-Breathlessness	5	–	0.14	0.3276	0.81 (0.76–0.85)
	Wheeze	1	–	0.06	0.1216	0.78 (0.71–0.82)

^aFor Days −2 to −1, n = 321 for all patients and n = 202 for morning PEF change < 15%
CI confidence intervals, E-RS Evaluating Respiratory Symptoms in chronic obstructive pulmonary disease, ICC intra-class correlations, PEF peak expiratory flow, RS respiratory symptom, SD standard deviation

ISSN: 1465-993X