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. Author manuscript; available in PMC: 2020 Dec 1.
Published in final edited form as: Pediatr Pulmonol. 2019 Sep 1;54(12):2011–2020. doi: 10.1002/ppul.24507

Table 3: Reliability testing of QOL-PCD scales:

Internal consistency measured by Cronbach’s α and test–retest reliability measured by intraclass correlation coefficients (ICC)

QOL-PCD1scales No. of Items Mean (SD) of
scales
Cronbach’s α2 ICC3 (95% CI)

Child QOL-PCD N=71 N=13
Physical functioning 5 79.15 (20.03) 0.76 0.540 (−0.507 to 0.806)
Emotional functioning 4 72.65 (16.07) 0.62 0.652 (−0.141 to 0.894)
Treatment Burden 5 56.34 (24.06) 0.66 0.895 (0.656 to 0.968)
Social functioning 5 79.71 (19.47) 0.61 0.890 (0.640 to 0.967)
Upper respiratory symptoms 5 66.48 (22.51) 0.76 0.807 (0.366 to 0.941)
Lower respiratory symptoms 6 63.07 (17.54) 0.70 0.791 (0.315 to 0.936)
Ears and hearing symptoms 4 74.65 (18.97) 0.60 0.841 (0.479 to 0.951)
Adolescents QOL-PCD N=85 N=17
Physical functioning 5 80.95 (23.67) 0.90 0.889 (0.692 to 0.960)
Emotional functioning 4 73.82 (19.76) 0.71 0.763 (0.321 to 0.917)
Treatment Burden 3 70.82 (23.96) 0.70 0.861 (0.586 to 0.953)
Role 3 80.78 (19.58) 0.71 0.842 (0.565 to 0.943)
Social Functioning 4 62.35 (23.27) 0.70 0.752 (0.314 to 0.910)
Vitality 3 59.22 (21.64) 0.76 0.859 (0.609 to 0.949)
Upper Respiratory Symptoms 5 65.33 (18.54) 0.70 0.734 (0.265 to 0.904)
Lower Respiratory Symptoms 7 58.23 (17.33) 0.82 0.716 (0.217 to 0.897)
Ears and Hearing 4 82.64 (20.67) 0.73 0.868 (0.623 to 0.954)
Parent Proxy N=68 N=13
Physical functioning 5 79.21 (21.26) 0.86 0.865 (0.557 to 0.959)
Emotional functioning 3 68.95 (16.69) 0.74 0.333 (−1.32 to 0.808)
Treatment Burden 4 59.68 (24.46) 0.78 0.607 (−0.286 to 0.880)
Social functioning 3 79.24 (22.05) 0.74 0.853 (0.519 to 0.955)
Health Perception 4 66.79 (17.25) 0.80 0.435 (−0.852 to 0.828)
Eating and weight 3 72.88 (28.95) 0.73 0.849 (0.505 to 0.954)
Upper respiratory symptoms 4 55.39 (22.98) 0.70 0.626 (−0.227 to 0.886)
Lower respiratory symptoms 6 58.66 (19.44) 0.84 0.645 (−0.162 to 0.892)
Ears and hearing symptoms 3 75.49 (22.52) 0.62 0.897 (0.662 to 0.969)
1

PCD, primary ciliary dyskinesia; QOL, quality of life.

2

Cronbach’s α >0.70 indicates good internal consistency.

3

ICC (intra-class correlation coefficient) >0.60 indicates good stability and >0.75 excellent stability of the scales.