Table 2.

Correlations between spirometry and IOS parameters in 301 asthmatic patients with effect size interpretation (low effect size for r value around 0.1, medium for r around 0.3, and large for r more than 0.5)

	FEV3/FEV6, %	FEF25-75, % pred	FEF50, % pred	FEF75, % pred	R5-R20, kPa·s·L−1	X5, kPa·s·L−1	AX, kPa·L−1
FEV3/FEV6, %		r = 0.745 p = 0.001	r = 0.764 p = 0.001	r = 0.739 p = 0.001	r = −0.334 p = 0.001	r = 0.364 p = 0.001	r = −0.351 p = 0.001
FEF25-75, % pred			r = 0.942 p = 0.001	r = 0.885 p = 0.001	r = −0.247 p = 0.001	r = 0.329 p = 0.001	r = −0.283 p = 0.001
FEF50, % pred				r = 0.828 p = 0.001	r = −0.332 p = 0.001	r = 0.397 p = 0.001	r = −0.360 p = 0.001
FEF75, % pred					r = −0.274 p = 0.001	r = 0.354 p = 0.001	r = −0.296 p = 0.001
R5-R20, kPa·s·L−1						r = −0.875 p = 0.001	r = 0.944 p = 0.001
X5, kPa·s·L−1							r = −0.899 p = 0.001
AX, kPa·L−1

FEV₃, forced expiratory volume in 3 s; FEV₆, forced expiratory volume in 6 s; FEF_25-75, forced expiratory flow between 25 and 75%; FEF₅₀, forced expiratory flow at 50%; FEF₇₅, forced expiratory flow at 75%; X5, 5 Hz reactance; AX, reactance area.