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

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

  Internal consistency Test-retest reliability
Day − 1 (N = 328) Day − 2 to Day − 1a
  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)
  1. aFor Days −2 to −1, n = 321 for all patients and n = 202 for morning PEF change < 15%
  2. 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