Although smoking is a well-known risk factor for the onset of airway diseases, the associations between smoking and asthma are inconsistent.
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. Ten years later, development of asthma was reported.
During 10-year follow-up, 105 men and 92 women reported the onset of physician-diagnosed asthma. Among men, current smokers at baseline had a significantly increased risk of asthma (hazard ratio [HR], 2.79), whereas women with a current or former history of smoking were at an increased but not significant risk of asthma (HR, 1.18).
A 2-5-fold increased risk of asthma was observed in men who smoked for more than 30 years or more than 21 cigarettes daily. These data suggest that smoking increases the risk of asthma onset in men.
Cigarette smoking and the adult onset of bronchial asthma in Japanese men and women. Nakamura K, Nagata C, Fujii K, Kawachi T, Takatsuka N, Oba S, Shimizu H. Ann Allergy Asthma Immunol. 2009 Apr;102(4):288-93.