Detection of Small Airway Dysfunction in Asymptomatic Smokers with Preserved Spirometry: The Value of the Impulse Oscillometry System

Figures & data

Table 1 Pearson (r) or Spearman (ρ) Correlation Coefficients and Corresponding p values of Pack/Year When Related to Spirometry and IOS Parameters in 75 Smokers

FVC (% pred)	r = −0.245	p = 0.034
FEV1 (% pred)	r = −0.373	p = 0.001
FEV1/FVC (%)	r = −0.516	p = 0.001
FEF25-75 (% pred)	r = −0.414	p = 0.001
FEV3/FEV6 (%)	r = −0.516	p = 0.001
R5 (kPa·s·L^−1)	r = 0.175	p = n.s.
R20 (kPa·s·L^−1)	r = −0.049	p = n.s.
R5-R20 (kPa·s·L^−1)	r = 0.284	p = 0.014
AX (kPa·L^−1)	ρ = 0. 235	p = 0.042
X5 (kPa·s·L^−1)	ρ = −0.189	p = n.s.
FRes (Hz)	ρ = 0. 283	p = 0.014

Note: Bold text indicates statistical significance.

Table 2 Pearson (r) or Spearman (ρ) Correlation Coefficients and Corresponding p values of FEV3/FEV6 When Related to IOS Parameters in 75 Smokers

R5 (kPa·s·L^−1)	r = −0.304	p = 0.008
R20 (kPa·s·L^−1)	r = −0.181	p = n.s.
R5-R20 (kPa·s·L^−1)	r = −0.333	p = 0.003
AX (kPa·L^−1)	ρ = −0. 293	p = 0.011
X5 (kPa·s·L^−1)	ρ = 0.252	p = 0.029
FRes (Hz)	ρ = −0. 310	p = 0.007

Note: Bold text indicates statistical significance.

Table 3 Characteristics of Healthy Controls and Asymptomatic Mild (<30 Pack/Year) and Heavy (≥30 Pack/Year) Smokers with Preserved Spirometry

	Never-Smokers (No. 34)	Mild Smokers (No. 39)	Heavy Smokers (No. 36)	p
Age (yr)	42±15	41±11	53±10	<0.01*
Sex (F%)	56	46	53	n.s.
BMI (Kg/m^2)	24±3	24±3	27±4	<0.01*
Pack/year	…	14.5±7	41.4±14	…
FVC (% pred)	112±14	107±12	101±13	<0.01^#
FEV1 (% pred)	107±13	106±12	97±13	<0.01*
FEV1/FVC (%)	0.81±0.07	0.81±0.05	0.76±0.05	<0.01*
FEV3/FEV6 (%)	0.81±0.07	0.81±0.05	0.76±0.05	<0.01*
FEF25-75 (% pred)	83±25	95±24	72±30	<0.01^§
R5 (kPa·s·L^−1)	0.348±0.09	0.351±0.09	0.426±0.16	<0.05*
R20 (kPa·s·L^−1)	0.322±0.07	0.326±0.08	0.354±0.10	n.s.
R5-R20 (kPa·s·L^−1)	0.026±0.03	0.025±0.03	0.071±0.09	<0.01*
AX (kPa·L^−1)	0.20 [0.14–0.34]	0.20 [0.12–0.37]	0.32 [0.16–0.81]	n.s.
X5 (kPa·s·L^−1)	−0.09 [−0.11–0.07]	−0.09 [−0.12–0.07]	−0.11 [−0.15–0.08]	<0.05*
FRes (Hz)	10.6 [9.0–13.8]	10.3 [8.9–14.8]	14.9 [9.2–18.4]	n.s.

Notes: Values are expressed as mean ± SD, median [25–75% percentile] or %. Bold text indicates statistical significance. *Heavy Smokers vs Healthy Subjects and Mild Smokers, #Heavy Smokers vs Healthy Subjects, §Heavy Smokers vs Mild Smokers.

Figure 1 Number of subjects categorized according to the presence of SAD (R5 – R20 > 0.07 kPa·s·L⁻¹) in 34 normal never-smokers, in 39 mild smokers (pack/year < 30), and in 36 heavy smokers (pack/year ≥ 30).