Allergic Rhinitis Epidemiology in Japan

: We epidemiologically surveyed allergic rhinitis nationwide, mailing questionnaires to 9,471 otorhinolaryngologists and their families nationwide in June 1998 responses by the end of September 1998: 42.8%, providing 17,301 subjects. Few differences were seen in the age composition between the subject population and the general Japanese population. Cedar pollinosis morbidity after adjustment for population distribution was 17.3%, higher overall on the Pacific Ocean side and in central districts of Japan compared to districts on the Sea of Japan and the Inland Sea and lower in high or low latitudes. By age, morbidity increased sharply among subjects in their teens and decreased among subjects in their 60s. Morbidity was high in districts of heavy cedar pollen dissemination. By housing, morbidity was high in the suburbs, followed by residential areas and cities. Pollinosis due to causes other than cedar pollen showed results similar to those for cedar pollinosis in morbidity by age and the relationship between the housing environment and morbidity, with morbidity after population distribution adjustment 11.7%. Morbidity of perennial allergic rhinitis after adjustment for population distribution was 19.8% was slightly higher than that of pollinosis. By age, morbidity increased sharply at 5 to 9 years of age, being highest in the young than in cedar pollinosis; no decrease in morbidity after age 60 was seen. Unlike cedar pollinosis, perennial allergic rhinitis showed no difference in morbidity by area or housing environment. The present survey using otorhinolaryngologists and their families nationwide as subjects enabled us to find areawise differences in morbidity for cedar pollinosis and perennial allergic rhinitis. Ours is useful epidemiologically in allergic rhinitis mainly for cedar pollinosis in Japan because it is superior to other questionnaires in response and because reply reliability is high.