Table 3.

Home spirometry variability over time.

Characteristics		All	Children	Teenagers	Adults	p
FEV1	Norm. Δmax (%)	49.6 [28.6; 68.1]	61.3 [48.5; 88.8]	49.5 [30.5; 71.3]	26.6 [21.0; 39.4]	<0.001a,b,c
	CoV (%)	11.5 [7.7; 16.1]	13.4 [10.6; 19.3]	10.7 [7.3; 14.3]	8.1 [5.9; 12.6]	<0.001a,b
	Norm. average variability (%)	8.9 [6.3; 12.9]	10.5 [8.4; 15.7]	7.6 [5.7; 10.0]	7.4 [5.1; 9.7]	<0.001a,b
FVC	Norm. Δmax (%)	44.9 [27.7; 65.2]	59.0 [42.5; 78.4]	43.1 [27.1; 65.2]	25.5 [18.7; 40.6]	<0.001a,b,c
	CoV (%)	10.0 [6.7; 14.5]	11.5 [8.8; 18.2]	9.3 [5.8; 14.3]	7.3 [5.3; 11.6]	<0.001a,b
	Norm. average variability (%)	8.1 [6.2; 11.6]	9.3 [7.3; 13.0]	7.0 [5.3; 9.9]	7.2 [5.1; 10.1]	<0.001a,b
FEF25-75	Norm. Δmax (%)	92.3 [58.0; 136.4]	131.8 [91.5; 171.6]	89.5 [58.5; 115.2]	61.5 [36.5; 80.3]	<0.001a,b
	CoV (%)	21.2 [15.1; 30.8]	28.0 [20.0; 36.1]	21.1 [14.0; 26.6]	16.0 [12.0; 21.6]	<0.001a,b
	Norm. average variability (%)	18.7 [13.4; 25.9]	23.9 [18.0; 29.8]	16.7 [11.8; 21.0]	14.4 [11.0; 18.8]	<0.001a,b
FEV1/FVC	Norm. Δmax (%)	34.7 [20.0; 53.5]	43.2 [28.7; 68.1]	34.2 [14.6; 53.9]	23.9 [13.4; 36.4]	<0.001a,b
	CoV (%)	8.0 [4.8; 11.8]	9.6 [6.4; 12.9]	7.2 [4.2; 10.8]	6.1 [4.3; 9.0]	0.001a,b
	Norm. average variability (%)	6.5 [4.7; 10.3]	8.7 [5.9; 11.5]	5.9 [3.6; 9.7]	5.8 [4.1; 8.0]	0.001a,b

Results are presented as medians with interquartile ranges [median (IQR25; IQR75)]. Comparison between groups were performed using the Kruskal-Wallis test with a Dunn post-test. p < 0.05 was considered significant. a Children vs. teenager; b Children vs. adults; c teenagers vs. adults.

FEV1, forced expiratory volume in one second; FVC, force vital capacity; FEF25-75, forced expiratory flow between 25% and 75% of vital capacity; Δmax, difference between the highest and the lowest values recorded; Norm., normalized; CoV, coefficient of variation.