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Background: The character or timing of chronic cough is considered to be unpredictable for diagnosing its cause. However, the associations of cough triggers with cough pathophysiology remains unknown., Methods: We developed a closed questionnaire listing 18 triggers that were reported by ≥1% of 213 patients in a retrospective survey. Using this questionnaire, patients with cough-predominant or cough-variant asthma (n = 140) and those with non-asthmatic cough (54) were asked whether their cough was induced by the listed triggers. Associations of triggers with causes of cough, airway sensitivity to inhaled methacholine, exhaled nitric oxide (NO) levels, number of sensitizing allergens, and scores from gastroesophageal reflux (GER) questionnaires were examined. Factor analysis was used to categorize variables, including the 12 most common cough triggers, diagnosis of asthmatic cough, airway sensitivity, and exhaled NO levels., Results: "Cold air" and "fatigue/stress" induced cough more often in asthmatic coughers than in non-asthmatic coughers. "Spices" and "meals" induced cough more frequently in GER-coughers (n = 19). Patients who marked "cold air" as the trigger were more sensitive to inhaled methacholine and showed higher exhaled NO levels than those who did not mark this trigger. The "post-nasal drip" trigger was associated with elevated exhaled NO levels, and this association was mainly exhibited by patients with cough-predominant asthma. The triggers "pollen" and "mold smell" were associated with a number of sensitizing allergens. The number of triggers was weakly associated with GER scores. By factor analysis, "cold air," "fatigue/stress," asthmatic cough, airway hypersensitivity, and elevated NO levels were categorized into the same factor., Conclusions: Several cough triggers may reflect the pathophysiology of prolonged or chronic cough.

Background: Chronic cough, which may be of asthmatic or nonasthmatic origin, is an important clinical issue. Airway inflammation, and remodeling demonstrated by subbasement membrane thickening has been associated with cough variant asthma (CVA) as well as with nonasthmatic chronic cough (NAC). CT studies have shown airway wall thickening in patients with asthma who wheeze. We examined airway wall thickness by CT in adult patients with chronic cough and examined its pathophysiologic implication., Methods: Nonsmoking, steroid-naïve patients with CVA (n = 27), NAC (n = 26), and healthy control subjects (n = 15) were studied. Airway dimensions were assessed by a validated CT technique, in which we measured airway wall area (WA) corrected by body surface area (BSA), the ratio of WA to outer wall area (percentage of wall area [WA%]), absolute wall thickness (T)/ square root BSA, and airway luminal area/BSA of a segmental bronchus. Correlations between CT parameters and clinical indexes such as disease duration and cough sensitivity were examined., Results: In patients with CVA, WA/BSA, WA%, and T/ square root BSA were all significantly greater than those in control subjects. In patients with NAC, WA/BSA and T/ square root BSA were significantly greater than in control subjects. The increase of WA/BSA and T/ square root BSA of NAC patients was less than that of CVA patients. In a subset of patients with NAC, WA% correlated with capsaicin cough sensitivity (n = 9, r = 0.75, p = 0.034)., Conclusions: Walls of central airways are thickened in patients with CVA, and also to a lesser degree in patients with NAC. Airway wall thickening in NAC may be associated with cough hypersensitivity.

Patients with cough variant asthma, a common cause of chronic cough, may develop wheezing. We examined the determinants of this phenomenon and achievement of remission in 42 patients. During 4 years after diagnosis, wheezing developed in 13 of the patients. Early inhaled corticosteroid treatment was inhibitory against the development of wheezing by univariate analysis and by multivariate analysis with an odds ratio of 0.12 (95% confidence interval, 0.02 to 0.87, p = 0.037). Remission was achieved in 7 patients, who were younger than those without remission by univariate analysis (p = 0.048). Early treatment with inhaled corticosteroid may prevent the progression of cough variant asthma to classic asthma.