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Table 5 Correlation analysis among traditional, eRIC, and fractional-order parameters, and the spirometric results

From: Combined forced oscillation and fractional-order modeling in patients with work-related asthma: a case–control study analyzing respiratory biomechanics and diagnostic accuracy

  FEV1 (L) FEV1 (%) FVC (L) FVC(%) FEV1/FVC FEF (L) FEF25–75 (%) FEF25–75/CVF
Resistive
 R0 − 0.33
ns
− 0.35
< 0.05
− 0.13
ns
− 0.11
ns
− 0.46
< 0.009
− 0.29
ns
− 0.44
< 0.02
− 0.43
< 0.02
 Rm − 0.27
ns
− 0.27
ns
− 0.15
ns
− 0.12
ns
− 0.31
ns
− 0.30
ns
− 0.33
ns
− 0.29
ns
 S 0.39
< 0.03
0.45
< 0.02
0.10
ns
0.12
ns
0.65
< 0.0001
0.22
ns
0.58
0.0005
0.62
0.0001
 R4 − 0.30
ns
− 0.31
ns
− 0.12
ns
− 0.08
ns
− 0.43
< 0.02
− 0.28
ns
− 0.42
< 0.02
− 0.40
< 0.03
 R12 − 0.29
ns
− 0.29
ns
− 0.16
ns
− 0.14
ns
− 0.32
ns
− 0.31
ns
− 0.35
< 0.05
− 0.30
ns
 R20 − 0.17
ns
− 0.13
ns
− 0.16
ns
− 0.10
ns
− 0.07
ns
− 0.31
ns
− 0.05
ns
− 0.43
< 0.02
 R4− R20 − 0.32
ns
− 0.37
< 0.04
− 0.01
ns
− 0.01
ns
− 0.66
< 0.0001
− 0.09
ns
− 0.55
< 0.002
− 0.64
< 0.0001
Reactive
 Xm 0.47
< 0.007
0.53
< 0.003
0.22
ns
0.24
ns
0.65
< 0.0001
0.24
ns
0.60
0.0002
0.62
0.0001
 Fr − 0.51
< 0.003
− 0.56
0.0008
− 0.25
ns
− 0.32
ns
− 0.63
0.0001
− 0.34
ns
− 0.66
< 0.0001
− 0.65
< 0.0001
 Cdyn 0.31
ns
0.33
ns
0.25
ns
0.24
ns
0.24
ns
0.21
ns
0.35
ns
0.26
ns
 Axt − 0.43
< 0.02
− 0.49
< 0.005
− 0.21
ns
− 0.24
ns
− 0.57
0.0006
− 0.23
ns
− 0.52
< 0.003
− 0.52
< 0.003
 Axi − 0.44
< 0.02
− 0.49
< 0.005
− 0.20
ns
− 0.22
ns
− 0.61
0.0002
− 0.23
ns
− 0.54
< 0.002
− 0.55
< 0.002
 Z4 − 0.36
< 0.05
− 0.39
< 0.03
− 0.18
ns
− 0.16
ns
− 0.47
< 0.008
− 0.25
ns
− 0.44
< 0.02
− 0.42
< 0.02
eRIC
 R − 0.05
ns
0.008
ns
− 0.10
ns
− 0.02
ns
0.11
ns
− 0.26
ns
− 0.01
ns
0.08
ns
 Rp − 0.37
< 0.04
− 0.41
< 0.02
− 0.10
ns
− 0.09
ns
− 0.62
0.0001
− 0.17
ns
− 0.53
< 0.002
− 0.59
0.0001
 Rt − 0.31
ns
− 0.31
ns
− 0.14
ns
− 0.09
ns
− 0.41
< 0.03
− 0.28
ns
− 0.42
< 0.02
− 0.40
< 0.03
 I 0.37
< 0.05
0.42
< 0.02
0.14
ns
0.21
ns
0.54
< 0.002
0.14
ns
0.48
< 0.006
0.53
< 0.002
 C 0.24
ns
0.30
ns
0.13
ns
0.17
ns
0.28
ns
0.14
ns
0.37
< 0.04
0.33
ns
FrOr
 G − 0.38
< 0.0026
− 0.35
0.0058
− 0.30
< 0.02
− 0.32
< 0.02
− 0.14 
ns
− 0.33
< 0.009
− 0.28
< 0.026
− 0.12
ns
 H 0.12
ns
0.07
ns
− 0.11
ns
0.00
ns
0.16
ns
013
ns
0.15 
ns
0.15
ns
 η − 0.40
< 0.002
− 0.28
< 0.03
− 0.32
< 0.02
− 0.19 
ns
− 0.36
< 0.004
− 0.31
< 0.02
− 0.34
< 0.007
− 0.33
< 0.009
  1. Significance was analyzed after Bonferroni correction. The significant associations are described in italic
  2. FEV1: forced expiratory volume in the first second; FVC: forced vital capacity; FEF: forced expiratory flow between 25 and 75% of the FVC; %: percentage of the predicted values; R0: intercept resistance; Rm: mean resistance; S: slope of the resistive values; R4: resistance in 4 Hz; R12: resistance in 12 Hz; R20: resistance in 20 Hz; Xm: mean reactance; Fr: resonance frequency; Cdyn: dynamic compliance; Axt: area under the reactance curve using the approximation by a triangle; Axi: area under the reactance curve using the integral based on the trapezoidal rule; Z4: impedance modulus in 4 Hz; eRIC: extended resistance–inertance–compliance model; FrOr: fractional order; R: central airway resistance; Rp: peripheral resistance; Rt: total resistance; I: pulmonary inertance; C: alveolar compliance; G: damping factor; H: elastance; η: hysteresivity coefficient