Abstract: Objective To identify patients with cough variant asthma(CVA) among those with chronic cough. Methods Data of the patients’ history, chest X-ray, pulmonary function(bronchial provocation test), screening allergen for 112 cases with chronic cough were collected and analyzed. Chi-square test was used for differences in rates. Results Fifty-eight cases were diagnosed as having CVA. Chest X-ray had no abnormalities, bronchial provocation test was positive in all these cases and allergen skin test was positive in 86.2%(50/58). Forty-two cases had predisposing factors. Allergen skin test was positive in 74.5%(38/42), and in 79％ of them(30/38) allergens related to the predisposition were identified. Allergen skin test was positive in 75%(12/16) of the cases who had no predisposing factors. Among 54 non-CVA cases chest X-ray had no abnormalities in 34 cases, lung marking increased in 17 cases, and emphysema in 3 cases. Bronchial provocation test was negative in all these cases and among 3 cases FEV1/FVC＜70% and FEV1＜80%. Allergen skin test was positive in 16.7%(9/54) cases. Forty-one cases had predisposing factors, and allergen skin test was positive in 12.2%(5/41) of the cases. Allergen skin test positive rate of the cases without predisposing factors was 30.8%(4/13). There was no significant difference in the positive rates of predisposing factors between the two group(χ²=0.180, P=0.672). However, chest X-ray findings(χ²=26.151, P=0.000), bronchial provocation test positive rate(χ²=112, P=0.000), allergen skin test positive rate(χ²=54.248, P=0.000), and allergen skin test positive rate of those without predisposing factors(χ²=5.673, P=0.017) had significant differences. Conclusion Allergen and predisposing factors were causally associated with CVA cases. In majority of cases who had no predisposing factors allergens could be detected. Bronchial provocation test and screening for allergen are important method to diagnose CVA.

Key words: chronic cough, cough variant asthma, Chest X-ray, bronchial provocation test, allergen skin test