Internal consistency of QOL-PCD scales measured by Cronbach's α and test–retest reliability measured by ICC
| QOL-PCD (adult) scales | No. of items | Mean (SD) of scales | Cronbach's α N=72 | ICC (95% CI) N=35 |
|---|---|---|---|---|
| Physical functioning | 5 | 70.51 (30.37) | 0.94 | 0.94 (0.89 to 0.97) |
| Emotional functioning | 5 | 73.68 (19.56) | 0.83 | 0.91 (0.82 to 0.95) |
| Treatment functioning | 4 | 60.80 (23.70) | 0.75 | 0.92 (0.82 to 0.96) |
| Social functioning | 3 | 38.11 (29.47) | 0.74 | 0.73 (0.47 to 0.87) |
| Role functioning | 4 | 64.23 (28.98) | 0.86 | 0.94 (0.88 to 0.97) |
| Health perception | 4 | 51.16 (26.32) | 0.83 | 0.91 (0.82 to 0.95) |
| Vitality | 3 | 53.76 (21.93) | 0.79 | 0.88 (0.75 to 0.94) |
| Upper respiratory symptoms | 4 | 45.83 (26.76) | 0.83 | 0.91 (0.81 to 0.95) |
| Lower respiratory symptoms | 6 | 47.30 (15.49) | 0.83 | 0.92 (0.85 to 0.96) |
| Ear and hearing symptoms | 2 | 61.81 (28.59) | 0.79 | 0.96 (0.87 to 0.97) |
Cronbach's α >0.7 indicates good internal consistency. ICC >0.6 indicates good stability and >0.75 excellent stability of the scales.
ICC, intraclass coefficients; PCD, primary ciliary dyskinesia; QOL, quality of life.