[Japanese cedar pollinosis is a risk factor for bronchial asthma in Japanese adult asthmatics].

It is well known that allergic rhinitis and asthma often coexist in the same patients. Here, we investigated the influence of Japanese cedar pollinosis on the exacerbation of asthma investigated by questionnaire, daily asthma diary, and peak expiratory flow (PEF) monitoring. Furthermore, airway responsiveness to histamine before pollen season was also investigated in some patients. 333 adult patients with asthma were enrolled into the study and 116 patients (34.8%) were suffering from Japanese cedar pollinosis diagnosed by the presence of nasal allergic symptoms during pollen season and high titer of Japanese cedar-specific IgE antibody. Exacerbation of asthma symptoms, including wheezing, dyspnea, cough, and sputum, was detected in 41 of 116 patients (35.3%) during pollen season. Decrease in morning PEF more than 10% compared with the baseline values before pollen season was observed in 13 of 41 patients (11.2% of total asthmatic patients who complicated with Japanese cedar pollinosis). No significant differences in airway responsiveness to histamine and the titer of Japanese cedar-specific IgE antibodies before pollen season were observed between the patients whose asthma exacerbated and the patients whose asthma was not exacerbated. These results suggest that Japanese cedar pollinosis is one of risk factors for asthma in Japanese adult patients with asthma.