Smoking and risk of cedar pollinosis in Japanese men and women.

BACKGROUND

Pollinosis induced by the cedar pollen antigen is the most common seasonal allergic reaction in Japan. We aimed to examine the relationship between smoking and risk of cedar pollinosis in a population-based cohort of the Japanese.

METHODS

Study subjects were 12,221 men and women from the Takayama Study cohort who were 35-69 years old at enrollment in 1992. A follow-up survey in 2002 was used to obtain information about four symptoms related to cedar pollinosis.

RESULTS

A total of 1,000 subjects had cedar pollinosis during the 10-year follow-up. As compared with those who had never smoked, current smokers at the baseline were at a significantly decreased risk of cedar pollinosis after controlling for covariates in men (hazard ratio [HR]: 0.64, 95% CI: 0.50-0.83) as well as in women (HR: 0.64, 95% CI: 0.47-0.88). There was a significant dose-response relationship between the risk of cedar pollinosis and the number of cigarettes smoked each day as well as with the number of years an individual had smoked. A significant risk reduction was observed among men and women who had continued to smoke cigarettes during the follow-up period in comparison with those who had never smoked. There was no risk increase for former smokers at the baseline as well as for those who quit smoking during the follow-up.

CONCLUSIONS

Some components of tobacco may protect against cedar pollinosis. Our finding could provide clues about therapeutic strategies for protection against cedar pollinosis.