Background: The relationship between chronic rhinosinusitis (CRS) and asthma has been known for a long time. However, no large studies on the relationship between CRS and lower airway diseases have been reported to date in Japan. Additionally, eosinophilic chronic rhinosinusitis (ECRS) in Japan is considered to be a subgroup of CRS with nasal polyps (CRSwNP) characterized by eosinophil-dominant inflammation. However, the diagnostic criteria of ECRS have not been established.
Methods: To investigate clinical and epidemiological features of patients with CRS from the aspect of their associations with lower airway diseases, 553 patients with CRS who visited one of six local university hospitals were examined and interviewed. Local eosinophilic infiltration was evaluated pathologically by examining NPs.
Results: The prevalences of olfactory dysfunction (OD) in the patients with nasal polyps (NPs) and those without NPs were 57.0% and 13.7%, respectively (p < 0.0001). The prevalence of asthma in all patients was 23.1%. Furthermore, the prevalences of NPs and OD in the patients with asthma and those without asthma were 81.0% and 50.1% (p < 0.0001) and 64.2% and 35.7% (p < 0.0001), respectively. 97.4% of the patients with asthma had ≥ 15% mucosal eosinophils, and 87.9% of the patients without asthma had <15% mucosal eosinophils.
Conclusions: Similar to the relationship between nasal allergy and asthma, CRSwNP may be applicable to the concept of "one airway, one disease".