An Association Between Upper and Lower Respiratory Tract Diseases

Both allergic rhinitis and bronchial asthma are inflammatory diseases in the respiratory tract. The upper and lower airways share many anatomical, physiological, and histological properties. A close relationship between allergic rhinitis and asthma has been established, and the “united airway disease hypothesis” proposes that upper and lower airway diseases are both manifestations of a single inflammatory process. Systemic therapies can resolve both diseases simultaneously. Although the association between asthma and allergic rhinitis has been examined extensively, the effect of other upper airway diseases on the onset and development of lower airway diseases is not fully understood. Rhinosinusitis is a common sinus infection, and recent studies have reported the possible role it plays on the pathogenesis of lower respiratory diseases. This article reviews the most up-to-date findings regarding the linkage and relationship between upper (rhinitis and rhinosinusitis) and lower (asthma and chronic obstructive pulmonary disease) airway diseases.