Relationships among allergic rhinitis, asthma, and chronic rhinosinusitis.

Background: Chronic rhinosinusitis (CRS) is a common disease in the United States. There are a significant number of patients with CRS who are refractory to standard medical and surgical therapy. Many of these patients also have comorbid allergic rhinitis (AR) and asthma, although the underlying pathophysiology that connects these three conditions remains unclear.