Analysis of the comorbidity of bronchial asthma and allergic rhinitis by questionnaire in 10,009 patients.

Bronchial asthma (BA) and allergic rhinitis (AR) are thought to share a common pathogenesis. However, reports concerning the comorbidity of the two diseases in a large-scaled population are rare in Japan. In the present study, we performed an analysis on the two diseases using questionnaires that addressed the diagnosis, symptoms and period of occurrence in more than 10,000 patients with BA or AR.Patients with BA (adult: n = 2,781, childhood: n = 3,283) and AR (n = 3,945) were enrolled in the present study during the 3 months from August 1, 2006 to October 31, 2006.Sixty one percent of the patients with adult BA showed symptoms of AR. Among them, 68% of the patients were diagnosed with AR. Among the patients with childhood BA, 68% showed AR symptoms and 60% were diagnosed with AR. On the other hand, 49% of AR patients showed BA symptoms and 35% of them were diagnosed with BA. The symptoms of both BA and AR in the BA and AR patients were frequent in two seasons, March and April, and September and October. In addition, BA and AR symptoms often co-occurred in the patients with BA and AR.Comorbidity of BA and AR was high in both populations of BA and AR. The symptoms of both BA and AR co-occurred on both a daily and seasonal basis. These results suggested that BA and AR share a common immuno-pathogenesis in the airway and need to be treated as a single airway disease.