Prevalence and clinical features of cough variant asthma in a general internal medicine outpatient clinic in Japan.
OBJECTIVE
The aims of the present study were to examine the prevalence and clinical features of cough variant asthma (CVA) among patients with chronic and persistent cough at an outpatient clinic in Japan, and the efficacy of treatment with an inhaled corticosteroid.


METHODS
This prospective study was conducted at a general internal medicine outpatient clinic in Japan over a 12-month period. CVA was diagnosed as chronic cough without wheezing or any apparent cause, that had persisted for more than 8 weeks, with a normal CXR and spirometry but with bronchial hyperresponsiveness to methacholine, and relief of cough after bronchodilator treatment. We also examined the effects of inhaled beclomethasone propionate on symptoms and differences in PEF between early morning and evening.


RESULTS
Of 55 patients suffering from chronic cough, 23 satisfied the criteria for CVA. Their cough occurred more frequently at night and early in the morning. Early morning PEF was significantly lower than evening PEF with a mean variability of 11.5 +/- 4.1%. Treatment with beclomethasone propionate improved coughing and significantly increased early morning PEF, reducing variability to less than 10%.


CONCLUSIONS
These findings suggest that CVA is most common among patients with chronic cough not due to any apparent cause. The efficacy of inhaled corticosteroid suggests that early intervention is effective in the treatment of CVA.
Shirahata
Kumiko
K
Department of General Internal Medicine, International Medical Center of Japan, Tokyo, Japan.
Fujimoto
Keisaku
K
Arioka
Hiroko
H
Shouda
Ryousuke
R
Kudo
Kouichirou
K
Ikeda
Shu-Ichi
S
D000280:Administration, Inhalation; D001249:Asthma / Q000150:complications / Q000453:epidemiology* / Q000503:physiopathology; D001507:Beclomethasone / Q000008:administration & dosage / Q000627:therapeutic use; D002908:Chronic Disease; D002940:Circadian Rhythm; D003371:Cough / Q000150:complications / Q000188:drug therapy / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000187:drug effects; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use; D006769:Hospitals, General; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital / Q000706:statistics & numerical data*; D015995:Prevalence; D011446:Prospective Studies; D016896:Treatment Outcome
D005938:Glucocorticoids; D001507:Beclomethasone