Upper airway disorders and asthma: a syndrome of airway inflammation.

OBJECTIVE: This article presents recent evidence of an upper and lower airway link. After reading this article, readers should have an understanding of the evidence for the pathologic relationship between asthma and upper airway disorders such as rhinosinusitis and allergic rhinitis. DATA SOURCES: Epidemiologic, pathophysiologic, and treatment outcomes studies were used. Only literature in the English language was reviewed. STUDY SELECTION: Material was taken from academic/scholarly journals.
RESULTS: Epidemiologic data indicate that asthma and allergic rhinitis frequently coexist, with rhinitis symptoms reported among 19 to 94% of asthma patients, and asthma reported among 19 to 38% of those with allergic rhinitis. Allergic rhinitis often precedes asthma symptomatology and has been shown to be a risk factor for the development of asthma. The severity of one's allergic rhinitis also has been shown to be directly correlated with asthma severity. Patients with allergic rhinitis exhibit increased eosinophil activity in both upper and lower airways. In these patients, nasal allergen challenge can induce increased bronchial hyperresponsiveness, suggesting that upper and lower airway disorders share common inflammatory features. Treatment of rhinitis symptoms has been shown to produce better asthma symptom control and, in a few studies, the improvement of airway function in patients with concomitant asthma.
CONCLUSIONS: Evidence suggests that upper respiratory disorders such as allergic rhinitis and rhinosinusitis are different facets of a larger systemic inflammatory syndrome involving both the upper and lower airways. Several important questions remain to be answered before the nature of the relationship between lower and upper airway disorders is fully understood.