Symptoms on Exposure to Nonallergic Stimuli

T he etiology of asthma is not known. Acute and chronic asthma can be triggered by several factors, including allergen exposure, upper respiratory tract infections (particularly viruses), exposure to irritants such as cold air, cigarette smoke, and other air pollutants, exercise, nonsteroidal antiinflammatory drugs, sulfites, and possibly emotional factors.’ While the exact role of allergen exposure in asthma is unknown, 75% to 85% of patients with asthma have positive immediate skin test reactions to common inhalant allergens.2 These and other observations demonstrate a strong and well established association between asthma and allergic disease. These figures may overestimate the true role of allergen exposure, but indicate the need for evaluation of the role of allergen exposure in the diagnosis and treatment of asthma. The extent to which allergy triggers asthma varies somewhat according to the age of the patient. In infants who have not yet become sensitized to aeroahlergens, respiratory infections are more likely to initiate asthma. In children beyond infancy, allergy assumes importance not only in persistence and severity, but also possibly in the development of the disease. Studies have reported that the severity of childhood asthma correlates with the number of positive skin tests.34 Children who have multiple positive skin tests may have asthma symptoms on a daily rather than intermittent basis.’ Exposure to aeroallergens may be important in adults under age 30. Occupational exposure may also account for up to 2% of all asthma.6 In contrast to findings in children, the presence of allergen skin test reactivity in adults does not appear to be associated with increased severity of asthma.