Characteristics of patients with chronic cough who developed classic asthma during the course of cough variant asthma: a longitudinal study.

BACKGROUND

Some patients develop asthmatic symptoms such as wheezing and dyspnea during the course of cough variant asthma (CVA), which are considered precursors of classical asthma.

OBJECTIVES

To identify the characteristics of such patients, we investigated the nature of CVA patients with or without developing bronchial asthma in the longitudinal study.

METHODS

In 28 CVA patients whom we could observe over 5 years, duration of coughing, physical examination findings, pulmonary function and bronchial hyperresponsiveness to inhaled methacholine were retrospectively assessed.

RESULTS

Of these patients with CVA, 10 developed the asthmatic symptoms of wheezing and dyspnea (precursors of classical asthma) over 5 years. All these 10 patients showed marked bronchial hyperresponsiveness; however, there were no significant differences in the bronchial responsiveness to methacholine between patients with precursors of classical asthma and pure CVA patients who did not wheeze. The duration of coughing had a significant relationship with precursors of classical asthma. Seven patients with precursors of classical asthma developed wheezing in the first year and 1 patient each in the second, third and fourth year.

CONCLUSIONS

These findings of a 5-year observation suggest that longer duration of coughing may be an important factor that develops precursors of classical asthma in patients with CVA.