Cough response to isocapnic hyperpnoea of dry air and hypertonic saline are interrelated

Cough

Table 1 Characteristics of the subjects.

	Asthma	Healthy control	p
n	36	14
Gender (male/female)	10/26	2/12
Age	40 (18-68)	37 (21-67)
Atopy^#	22	5
Smoking (mean pack years)
Current	9 (6)	0
Previous	3 (11)	0
Use of inhaled corticosteroids (ICS)	24	0
Daily dose of ICS	541 ± 391 μg	-
ASA intolerance	3	0
Use of ACE inhibitors	5	0
Exhaled nitric oxide	18.4 ± 15.0	14.6 ± 6.59	0.376
FEV₁ (% from predicted)^¶	90.0 (67-122)	92.8 (78-110)	0.418
Mean daily PEF variability (%)	7.90 ± 5.75	-
Needed rescue medication doses during pre-test week	0.83 (0-4)	-
CDR Hypertonic saline coughs/(mOsm/kg)	0.012 ± 0.010	0	<0.001
CDR Hyperpnoea of dry air coughs/MVV%	0.464 ± 0.514	0.011 ± 0.024	<0.001

Age, FEV₁ and needed rescue medication doses mean (range). ^# Atopy was assessed as ≥3 mm mean wheal diameter in the skin prick test to at least one common aeroallergen. Daily dose of ICS, exhaled NO, mean daily PEF variability and CDR (cough-to-dose ratio) mean ± SD. ^¶ Reference values are those of Viljanen et al. [34]