Allergic rhinitis, asthma, and rhinosinusitis: diseases of the integrated airway.

OBJECTIVE To review data supporting the integrated airway hypothesis. Allergic rhinitis, rhinosinusitis, and asthma are common conditions associated with significant morbidity and health care costs. A theory has been developed suggesting that these conditions may be manifestations of an inflammatory process within a continuous airway rather than fully separate diseases. Based on this theory, the presence of upper airway symptoms may negatively influence the natural course of lower airway disease. Controlling upper airway inflammation and symptoms among asthma patients may help improve health and economic outcomes. SUMMARY Further clarifying and understanding the relationship between diseases of the upper and lower respiratory tracts is important because of the prevalence of allergic rhinitis, rhinosinusitis, and asthma and the resulting burden on patients and the health care system. Recent progress in understanding the biology of airway disease has identified inflammation as playing a critical and integrating role in these diseases; however, other important questions remain, including factors that determine the clinical phenotype in allergic airway disorders and optimal treatment approaches. CONCLUSIONS Several recent studies have suggested that allergic rhinitis, rhinosinusitis, and asthma may be manifestations of a common underlying pathology, but there are many unanswered questions. More studies are needed to better define all the underlying pathologic mechanisms as well as treatments to optimize outcomes for patients with allergic rhinitis, rhinosinusitis, and asthma.