Allergic rhinitis (AR) is usually defined as an inflammatory disease of the nasal mucosa induced by an interaction of environmental allergens and IgE in sensitized patients. Its symptoms are sneezing, nasal itching, rhinorrhoea and nasal obstruction. Allergic rhinitis affects approximately 20- 30% of the population worldwide and its prevalence is increasing. Isolated AR is rare and it actually has to be considered as a systemic allergic disease, associated to comorbidities, such as conjunctivitis, chronic middle ear effusions, irregular sleep, sinusitis, lymphoid hypertrophy with obstructive sleep apnoea. The most relevant comorbidity is asthma, a heterogeneous disease, usually characterized by chronic airway inflammation in which many cells and cellular elements play an important role. Bronchial asthma is characterized by bronchial hyper-reactivity and symptoms may be triggered or worsened by factors such as viral infections, allergens, tobacco smoke, exercise and stress. A state of "minimal persistent inflammation" is permanently maintained in the lower respiratory tract of asthmatic individuals. The diagnosis of asthma is based on evidence of variable airflow limitation tested with spirometry and a positive bronchodilation reversibility test. Skin prick tests (SPTs) are widely used to demonstrate an immediate IgE-mediated allergic reaction. They represent a major diagnostic tool in the field of allergy. Skin prick tests have a high specificity and sensitivity for the diagnosis of inhalant allergens. Immunotherapy (AIT) for allergic diseases has entered in a new age characterized by the development of a few innovative therapeutic classes of standardized allergen formulations registered. Clinical randomized trials have demonstrated the efficacy of AIT in allergic rhinitis in children and in adults, expressed in terms of reduction of symptom score and use of rescue medication. The efficacy is confirmed both for subcutaneous (SCIT) and sublingual (SLIT) immunotherapy in adults and in pediatric patients. The long lasting effect of AIT after its discontinuation is an important added value of this therapy. Controlled studies are available, where the carry-over effect of AIT is demonstrated for two years after discontinuance. The capacity to prevent new sensitizations, and to modify the evolution of the disease from the rhinitis to asthma are two important features of AIT. Allergen immunotherapy showed preventive capacity and also a carryover effect once treatment is discontinued.
Part of the book: Primary Care in Practice