Sometimes seasonal symptoms suggest the importance of airborne allergens, but perennial symptoms can also be caused by allergenic triggers. With regard to natural history, asthma commonly begins in early childhood and affects boys more frequently than girls. When children with asthma mature to adults, about one fourth will have persistent symptoms of asthma, one fourth will be free of symptoms, and one half will experience infrequent or episodic symptoms.1 Children with severe asthma are more likely to experience persistent asthma as adults.2 Many conditions are easily misinterpreted as asthma, and appropriate identification can lead to a dramatic reorganization of the treatment plan. The hallmark of asthma has always been the concept of reversible airway obstruction. However, with the recognition that asthma is an inflammatory process, the importance of one or more pathologic features, including epithelial damage, increased vascular permeability, mucosal edema, mucus production, and the infiltration of a heterogenous cellular infiltrate, are now more fully appreciated.
Inflammation can result from immunologic or nonimmunologic causes.
It is also recognized that nonallergic stimuli may be responsible for similar inflammatory mechanisms. The bronchial lavage fluid and bronchial tissue in patients during late responses are characterized by the presence of eosinophils, neutrophils, monocytes, and T-lymphocytes. The role of inflammation in the pathogenesis of asthma should be considered when a treatment regimen for an individual patient is recommended. The variable clinical pattern and natural history of asthma impose the need to individualize treatment with regard to choice of medication, avoidance of allergenic and non-allergenic triggers and immunotherapy, when adequate avoidance is not possible. The relative safety of the therapeutic alternatives influences the therapeutic decisions that are made in striving for these goals.