The relationships of rhinitis and asthma.

Rhinitis and asthma are common airway conditions; however, recent data suggest that they both can be clinical manifestations of a systemic inflammatory process within the respiratory tract. The link between these two airway disorders has been called the "integrated airway hypothesis." Several epidemiological studies have established an association between rhinitis and asthma, and approximately 19-38% of patients with allergic rhinitis have coexistent asthma. Additionally, an understanding of the biology of the two airway disorders suggests that systemic inflammation after local allergen challenge links the upper and lower airways. More recently, data from clinical studies in patients with rhinitis and coexistent asthma have highlighted that an improved control of nasal symptoms frequently results in improved asthma symptom scores. To clarify the relationships between upper and lower airway disorders and to establish the potential benefits of an integrated airways management approach, additional studies are warranted.