E-RS reliability: internal consistency and test-retest reproducibility
| Internal consistency (n=188) | Reproducibility (Day 1 and Day 2) (n=76)† | ||||||
|---|---|---|---|---|---|---|---|
| E-RS* scale (# items) | Cronbach's α | ICC‡ | Day 1 mean (SD) | Day 2 mean (SD) | Difference (SD) | p Value§ | Effect size |
| RS-Total Score (11) | 0.88 | 0.90 | 9.62 (6.24) | 9.66 (6.36) | −0.04 (2.88) | 0.91 | −0.01 |
| RS-Breathlessness (5) | 0.86 | 0.86 | 5.07 (3.65) | 4.87 (3.63) | 0.20 (1.95) | 0.38 | 0.05 |
| RS-Cough & Sputum (3) | 0.73 | 0.87 | 2.82 (2.30) | 2.88 (2.18) | −0.07 (1.15) | 0.62 | −0.03 |
| RS-Chest Symptoms (3) | 0.81 | 0.82 | 1.74 (1.86) | 1.91 (2.07) | −0.17 (1.18) | 0.21 | −0.09 |
| Reproducibility (Day 1 and Day 7) (n=171)¶ | |||||||
| RS-Total Score | 0.73 | 11.9 (6.77) | 12.1 (7.22) | −0.15 (5.14) | 0.70 | −0.02 | |
| RS-Breathlessness | 0.71 | 5.95 (3.75) | 6.09 (4.13) | −0.15 (3.00) | 0.53 | −0.04 | |
| RS-Cough & Sputum | 0.69 | 3.51 (2.28) | 3.42 (1.96) | 0.09 (1.67) | 0.49 | 0.04 | |
| RS-Chest Symptoms | 0.62 | 2.45 (2.11) | 2.54 (2.27) | −0.09 (1.92) | 0.52 | −0.04 | |
*Ranges: RS-Total 0 to 40; RS-Breathlessness 0 to 17; RS-Cough & Sputum 0 to 11; RS-Chest Symptoms 0 to 12; higher scores=more severe symptoms.
†Intraclass correlation coefficient.
‡Participants reporting ‘no change’ between the two consecutive days.
§p value from paired t test.
¶Participants completing the diary at Day 1 and Day 7.
E-RS, Exacerbations of Chronic Pulmonary Disease Tool-Respiratory Symptoms; ICC, intraclass correlation coefficient.