Airway oxidative stress in chronic cough

Cough

Table 1 The basic characteristics of the subjects

Characteristic	Subjects with chronic cough (N = 43)	Healthy subjects (N = 15)
Age (years)	55.6 ± 1.9	52.7 ± 4.1
Females – number (%)	32 (74)	11 (73)
Ex smokers – number (%)	20 (47)	4 (27)
Atopic patients – number (%)	14 (33)	1 (7)
Duration of cough (years)	8.5 ± 1.5	ND
Most probable cause of cough^a,	Rhinitis 22 (51)	ND
- number (%)	Esophageal reflux 14 (33)
	Asthma 9 (21)
Leicester questionnaire total score	13.2 ± 0.5	ND
Cough sensitivity to hypertonic saline (coughs/Osmol/kg)	7.24 ± 1.03	ND
Histamine PD₁₅ (mg)^b	1.28 ± 1.20	ND
Nitric oxide concentration (ppm)	16.8 ± 2.0	ND
FEV₁ (% of predicted)	93.7 ± 1.8	ND
PEF variation in ambulatory monitoring (%)	7.13 ± 0.68	ND

Continuous data is expressed as means and standard errors. ND = not done; FEV₁:= forced expiratory volume in one second; PD₁₅ = provocative dose of histamine to induce a 15% fall in FEV₁. PEF = peak expiratory flow.
^aBased on the results of the Cough Clinic diagnostic questionnaire. Two patients had more than one most probable cause.
^bAmong subjects without a 15% fall in FEV₁ in response to histamine, an arbitrary value of 3.2 mg was used as PD₁₅. Histamine challenge was missed in one patient due to technical reasons.