Table 3

Correlation between the forced expiratory volume in one second (FEV₁) per cent predicted and normalised phase-III slopes (Sn_III) at rest, after cold dry-air hyperventilation challenge (CACh), and after β₂-agonist therapy, and between the changes in FEV₁ % pred and the normalised phase-III slopes from baseline to postchallenge, in the whole study population, and in the three subgroups

	All subjects	Subgroup
		Major responders	Minor responders	Nonresponders
Subjects n	55	12	16	27
Resting
FEV₁ % pred vs
SF₆ Sn_III·L⁻¹	ns	ns	ns	ns
He Sn_III·L⁻¹	ns	ns	ns	ns
(SF₆-He) Sn_III·L⁻¹	ns	ns	ns	ns
Post-CACh
FEV₁ % pred vs
SF₆ Sn_III·L⁻¹	0.38 (<0.001)	0.35 (0.044)	ns	ns
He Sn_III·L⁻¹	0.48 (<0.001)	0.55 (0.005)	ns	ns
(SF₆-He)·Sn_III·L⁻¹	0.23 (<0.001)	0.33 (0.049)	ns	ns
Post-β₂ therapy
FEV₁ % pred vs
SF₆ Sn_III·L⁻¹	ns	0.51 (0.013)	ns	ns
He Sn_III·L⁻¹	ns	0.60 (0.005)	ns	ns
(SF₆-He) Sn_III·L⁻¹	ns	ns	ns	ns
Change from resting to post-CACh
FEV₁ % pred vs
SF₆ Sn_III·L⁻¹	0.60 (<0.001)	ns	ns	ns
He Sn_III·L⁻¹	0.70 (<0.001)	ns	ns	ns
(SF₆-He) Sn_III·L⁻¹	0.36 (0.001)	0.50 (0.010)	0.27 (0.040)	ns

Data are presented as r² (p-values) from the Pearson correlation test
vs: versus
SF₆: sulphur hexafluoride
He: helium
ns: nonsignificant