Epidemiology of Japanese cedar pollinosis throughout Japan

Japanese cedar pollinosis (JCP) is a common disease posing a major public health problem in Japan. For health care policy planning and development of new treatment modalities, investigation of the accurate prevalence and current status of JCP nationwide is imperative.

To ascertain the prevalence and the current status of JCP in Japan with use of a cross-sectional random sampling method.

In a nationwide survey conducted shortly after the peak pollen season, self-evaluation questionnaire were mailed to 10,920 subjects from 390 of 3,370 places in 12 regions in Japan.

The response rate was 53.7%, and the usable response rate was 51.5%. The age-adjusted prevalence was 19.4%; the estimated prevalence was 13.1% after adjustment for misdiagnosis, incorrect answers, response rate, and case mix. JCP was most prevalent in the Kanto, Tokai, and Kinki areas and in working adults rather than in children or subjects ages 60 to 79 years. Total pollen count during the pollen season correlated well with the prevalence of JCP in individual regions. In subjects with JCP, nasal symptom were more severe than eye symptoms, 62.5% had severe or moderate interference with daily activities and consulted physicians, 54.1% took prescribed drugs, and 82% used some method to avoid pollen.

The age-adjusted prevalence of JCP was 19.4% of the Japanese population, and estimated prevalence after correction of possible biases was 13.1%. Prescribed drugs treated approximately 60% of subjects with JCP, and 80% of subjects tried self-care by avoiding pollen.