Table 3.

Single Correlations (3a) and Multiple Regression Analysis (3b) of E/I LF with Clinical Factors and Impulse Oscillometry Parameters.

3a
Single correlations
parameters	r	p value
R5 In.	0.36	0.035
R5 Ex.	0.53	0.001
Δ R5	0.48	0.004
R20 In.	0.37	0.033
R20 Ex.	0.4	0.018
Δ R20	0.28	0.10
(R5-R20) In.	0.15	0.40
(R5-R20) Ex.	0.48	0.004
Δ (R5-R20)	0.36	0.035
X5 In.	-0.28	0.11
X5 Ex.	-0.49	0.004
∆ X5	-0.12	0.51
AX In.	0.28	0.10
AX Ex.	0.47	0.005
Δ AX	0.22	0.21
Fres In.	0.31	0.08
Fres Ex.	0.47	0.005
Δ Fres	0.35	0.04
age	-0.24	0.17
Disease period	0.48	0.004
Smoking history	0.28	0.12
FEV1.0, %predicted. (%)	-0.53	0.001
50, %predicted. (%)	-0.36	0.036
25, %predicted. (%)	-0.31	0.078
logPC20	-0.43	0.001
log IgE	0.36	0.036

3b
	Partial regression coefficient	Standardised partial regression coefficient (β)	SE	t value	p value
Adjusted R^2=0.528
SEX[F]	-0.112	-0.396	0.034	-3.29	0.003
FEV1,%predicted	-0.006	-0.560	0.001	-4.67	<0.0001
ΔR5	0.813	0.266	0.368	2.21	0.035
Adjusted R^2=0.518
SEX[F]	-0.097	-0.344	0.036	-2.7	0.011
FEV1,%predicted	-0.006	-0.556	0.001	-4.58	<0.0001
ΔR5-R20	1.432	0.260	0.702	2.04	0.050
Adjusted R^2=0.495
SEX[F]	-0.112	-0.398	0.035	-3.19	0.003
FEV1,%predicted	-0.006	-0.553	0.001	-4.45	0.0001
ΔFres	0.011	0.203	0.007	1.61	0.117

E/I LF: expiration-to-inspiration sound power ratio in the low-frequency range, R5: resistance of the respiratory system at 5 Hz, In: inhalation, Ex: exhalation, Δ: the differences between exhalation and inhalation, R20: resistance of the respiratory system at 20 Hz, R5 - R20: difference between R5 and R20, X5: reactance of the respiratory system at 5 Hz, AX: reactance area, Fres: resonant frequency of reactance, FEV_1.0: forced expiratory volume in one second, ₅₀and ₂₅: maximal expiratory flows at 50% and 25% of FVC, respectively, PC20: provocative concentration of acetylcholine causing a 20% decrease in the FEV_1.0