A clinical approach to allergic rhinitis

F or about one in five people in Australia, the external world can be an unpleasant and potentially dangerous place because of allergic disease. Already one of the most common chronic noncommunicable conditions in the world, allergic disease is predicted to increase in prevalence by approximately 70% in the next 35 years.1 Inadequately treated allergic disease creates a significant economic burden throughout the western world through absenteeism and reduced productivity as more than 75% of those with allergic disease are aged between 15 and 64 years. In Australia in 2007, the estimated financial cost to each patient with an allergy was nearly $2000 (direct and indirect costs).1 Of the broad spectrum of allergic diseases, allergic rhinitis is the most common in this country, being about 50% more prevalent than asthma, the next most common allergic disorder.1 Worldwide, between 10 and 30% of adults are affected by allergic rhinitis, and prevalence in Australia and New Zealand is among the highest reported.2 A significant contributor to morbidity and loss of productivity in patients with allergic rhinitis is sleep disturbance and fatigue, caused by both the condition itself and the side effects of pharmacotherapy, particularly with the older first-generation antihistamines. The clinical features of allergic rhinitis have been described for many centuries, and in 1929 were summarised by Hansel as: ‘The three cardinal symptoms in nasal reactions occurring in allergy are sneezing, nasal obstruction and mucous discharge’.3 Additional clinical features of allergic rhinitis include itchy nose, itchy throat, itchy and watery eyes (allergic conjunctivitis), and postnasal drip. By definition, allergic rhinitis is the symptomatic response to localised IgE-mediated inflammation triggered by exposure to an aeroallergen to which the individual is sensitised. Therefore, exposure to an aeroallergen is required. These aeroallergens may be present all year round (perennial; e.g. house dust mite, pets, moulds) or at certain times of the year (seasonal; e.g. pollens), or only in certain occupations (occupational; e.g. mice for laboratory workers, or chemicals). It is important to be mindful that not all individuals with congestion and nasal discharge have allergic rhinitis. Nonallergic rhinitis is a significant subset of rhinitis, with about 50% of Key points