Cigarette smoking and the adult onset of bronchial asthma in Japanese men and women.
BACKGROUND
Although smoking is a well-known risk factor for the onset of airway diseases, the associations between smoking and asthma are inconsistent.


OBJECTIVE
To examine the relationship of smoking in adulthood with the occurrence of asthma in Japanese individuals.


METHODS
A total of 6,674 men and 8,301 women from a population-based cohort in Takayama, Japan, participated in this prospective study. Information on smoking was collected via a baseline questionnaire in 1992. In 2002, development of asthma and the time of physician diagnosis were reported.


RESULTS
During 10-year follow-up, 105 men and 92 women reported the onset of physician-diagnosed asthma. Among men, compared with never smokers, current smokers at baseline had a significantly increased risk of asthma after adjustment for covariates (hazard ratio [HR], 2.79; 95% confidence interval [CI], 1.18-6.55), whereas women with a current or former history of smoking were at an increased but not significant risk of asthma (HR, 1.18; 95% CI, 0.58-2.38). An approximately 2- to 5-fold increased risk of asthma was observed in men who smoked for more than 30 years or more than 21 cigarettes daily, with a nonsignificant linear trend, but there was no dose-response relationship in current-smoking women. Ever-smoking women with husbands who were ever smokers had a higher risk of asthma (HR, 2.02; 95% CI, 0.72-5.65) than never-smoking women with husbands who had never smoked either.


CONCLUSIONS
These data suggest that smoking increases the risk of asthma onset in men.
Department of Epidemiology and Preventive Medicine, Gifu University Graduate School of Medicine, Gifu, Japan. kozuen@gifu-u.ac.jp
Kozue
K
Nakamura
Chisato
C
Nagata
Kaori
K
Fujii
Toshiaki
T
Kawachi
Naoyoshi
N
Takatsuka
Shino
S
Oba
Hiroyuki
H
Shimizu
D001249:Asthma / Q000453:epidemiology* / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*