Isocapnic Cold Air Challenge in Patients with COPD: Are There any Predisposing Factors?

Figures & data

Table 1 Subjects' characteristics

	COPD
	All (n = 92)	CACh(+) (n = 15)	CACh(−) (n = 15)	p value
Age (years)	65 (7) (45–78)	62 (10) (46–78)	65 (4) (58–71)	0.79
FEV1 (% predicted)	69.5 (5) (60–78)	67(5) (60–78)	69(5.5) (60–78)	0.26
ΔCFEV1%	5(5) (0–22)	15(4) (10.5–22)	2.65(2) (0–6)	< 0.0001
Smokin (pack-years)	38 (6) (29–56)	39 (5) (32–50)	37 (7) (29–54)	0.69
Atopy/Total IgE (IU/mL)	(−) 34 (6) (27–51)	(−) 38 (8) (29–51)	(−) 32 (5.5) (27–44)	0.34
BMI(Kg/m^2)	28(4) (20–39)	26 (2) (22–29)	26.5 (2) (24–29)	0.62

Values are expressed as mean SD with ranges in parenthesis, p value is for comparison between the 2 subgroups. Δ_CFEV₁% = Δ FEV₁% after cold air challenge Atopy was assessed as the results of negative skin prick tests to 6 common aeroallergens.

Table 2 Correlations between Δ_CFEV₁and the parameters that might affect its values in the 30 study subjects of both groups.

Variables	ΔCFEV1
FEV1 % baseline	rs^2 = 0.05 (p = 0.2)
FEV1/FVC %	rs^2 = 0.04 (p = 0.5)
PD20 (μ g)	rs^2 = −0.03 (p = 0.5)
ECP (μ g/L)	rs^2 = 0.12 (p = 0.33)
Reversibility %	rs^2 = 0.04 (p = 0.19)
ΔTFEV1 (L) 2nd hour	rs^2 = 0.1 (p = 0.09)
ΔTFEV1 (L) 3rd hour	rs^2 = 0.09 (p = 0.1)
Trough ΔTFEV1 (L)	rs^2 = 0.62 (p < 0.0001)
ΔPFEV1 (L) 2nd hour	rs^2 = 0.08 (p = 0.15)
ΔPFEV1 (L) 3rd hour	rs^2 = 0.09 (p = 0.11)
Trough ΔPFEV1 (L)	rs^2 = 0.1 (p = 0.09)

Bold letters indicate significant correlations. Δ FEV₁ after cold air challenge = Δ _CFEV₁, Δ FEV₁ after tiotropium = Δ_TFEV₁, Δ FEV₁ after placebo = Δ_PFEV₁.

Figure 1 Correlation between trough Δ_TFEV₁ (in L) and Δ_CFEV₁ % in the whole group of 30 patients (r_s² = 0.62, p < 0.0001).

Table 3 Study variables in the 2 subgroups

	COPD
	CACh(+) (n = 15)	CACh(−) (n = 15)	p value
FEV1/FVC %	63.5 (5) (54–70)		67 (4) (60-70)
PD20 (μ g)	0.53 (0.12) (0.41–0.91)		0.52 (0.06) (0.44–0.67)
ECP (μ g/L)	5.5 (2.5) (2.6–10.5)		5.9 (3) (2.3–11.4)
Reversibility %	6 (4.5) (0–14)		7.5 (3) (3–15)
ΔTFEV1, (L) 2nd hour	0.13 (0.02) 0.09–0.19		0.14 (0.02) 0.11–0.17
ΔTFEV1, (L) 3rd hour	0.13 (0.02) 0.09–0.175		0.135 (0.02) 0.09–0.165
Trough ΔTFEV1, (L)	0.03 (0.02) 0.01–0.07	0.085 (0.02) 0.045–0.11	< 0.0001

Values are expressed as mean SD with ranges in parenthesis, p value is for comparison between the 2 subgroups. Bold letters indicate significant differences. Δ FEV₁ after tiotropium = Δ_TFEV₁.

Figure 2 Tiotropium inhalation in patients with CACh (+) (filled circles) and CACh (−) (open circles). The Δ FEV₁ did not differ significantly in patients with CACh (+) at 2 and 3 hours after the inhalation compared to those with CACh (−) (p = 0.9, and p = 0.27, respectively). Patients with CACh (−) had significantly higher values 24 hours post-inhalation Δ FEV₁, compared to those with CACh (+) (*p = 0.01). The inhalation of placebo had no significant bronchodilating effect in patients with CACh (+) (filled triangles) and CACh (−) (open triangles), and the Δ FEV₁ values were lower than the ones measured after tiotropium at all time points.