Allergic rhinitis and its impact on asthma: an evidence-based treatment strategy for allergic rhinitis

The overall pathogenic view of respiratory allergy has deeply changed and evolved during the last ten years. Much emphasis has been laid to the relationship between rhinitis and asthma, which is between the upper and the lower respiratory airways. This strict link has been evidenced through clinical observations and epidemiological studies and also on the basis of immunological observations and outcomes of therapy. Furthermore, the frequent co-existence of rhinitis and asthma (up to 80 percent of asthmatic patients have co-existing allergic rhinitis, while up to 40 percent of allergic rhinitis patients have asthma, the coexistence of sinusitis and asthma, the presence of rhinitis as a risk factor for developing asthma, further emphasize this link and together lead to the operative definition of Allergic Rhinobronchitis or, United Airways Disease (UAD). The strict link existing between upper and lower respiratory tract can be also regarded from the viewpoint of therapeutical outcomes. The more detailed knowledge of the intricate mechanisms sustaining allergic inflammation in the respiratory tract (i.e. antigen presentation, cytokines, chemokines and adhesion molecules) has clarified the functional relationships between nose and lung. Thus allergic rhinitis or asthma is not a disease confined to a specific target organ, but rather a disorder of the whole respiratory tract, with a range of clinical manifestations, leading to relevant diagnostic and therapeutic implications as indicated in the WHO Initiative ARIA, the first evidence-based guideline emphasizing the impact of allergic rhinitis on asthma and where a step-wise treatment strategy targeting both the upper and lower airway effectively has been proposed. Moreover, the use of novel potential therapies that target both rhinitis and asthma like antileukotrienes or anti-IgE are indeed a future strategy.