Asthma is a chronic disease of multifactorial origin whose prevalence has continued to increase despite our increased understanding of its pathophysiology and the development of new pharmacologic weapons to fight it. Prevalence studies report that up to 16 million Americans have asthma, including 6 million children.1
This is not a local phenomenon. Comparisons of prevalence rates for asthma from the European Community Respiratory Health Survey2 of asthma in adults, which includes data from 48 centers in 22 countries (predominantly in Western Europe), and the International Study of Asthma and Allergies in Childhood,3 which includes data from 120 centers in 48 countries, show 5 striking patterns: (1) the prevalence of asthma is increasing worldwide; (2) asthma is generally more common in Western countries and less common in developing countries; (3) asthma is more prevalent in English-speaking countries; (4) the prevalence of asthma is increasing in developing countries as they become more Westernized or as communities become more urbanized; and (5) the prevalence of asthma has been accompanied by an increase in atopic diseases such as allergic rhinitis and atopic dermatitis worldwide.
The epidemiologic link between allergic respiratory disorders of the upper airway, specifically allergic rhinitis, and asthma was further highlighted in a study done by Settipane et al.4 involving 1,836 Brown University freshmen evaluated in the early 1960s. These students did not have asthma. After 23 years, 694 were available for follow-up. Seventeen of 162 students (10.5%) who had allergic rhinitis had asthma, whereas only 19 of 528 students (3.6%) who did not have allergic rhinitis had asthma. The authors concluded that the likelihood of asthma developing is three times greater when one has allergic rhinitis.
In separate studies, allergic rhinitis has been diagnosed in up to 80% of patients with asthma, and asthma has been diagnosed in up to 58% of patients with allergic rhinitis.5'6 Additionally, allergic rhinitis occurs simultaneously with or precedes asthma in up to 64% of patients.7
The relationship between upper and lower airway disease can be traced back to as early as 200 AD when Galen promoted purging the nostrils of secretions to "relieve the lungs."8 Kratchner in 1870 and Dixon in 1903 showed that stimulation of the upper airway in cats led to increased pulmonary resistance and bronchoconstriction.9
In 1920, Keller10 reported nasal pathology in 86 of 100 case histories involving chest symptoms that he reviewed. He theorized that mouth breathing due to chronic nasal congestion prevented proper moistening, warming, and filtering of the air and that this contributed to asthma. Bishop, in the same publication, opined that "reported failure to relieve asthma through the treatment of the sinuses argues not so much against the sinuses as a causal factor of the disease as against the thoroughness of the treatment directed against the sinuses."11
In this issue of Pediatric Annals, we will look further into the link between allergic disorders of the upper airway and asthma. We will expound on existing epidemiologic data, which establish the association between the two. We will also examine the putative pathogenic mechanisms that may explain how nasal pathology in allergic rhinitis influences, contributes to, and possibly causes acute and chronic lower airway inflammation and how it alters the dynamics of the lower airway, making it more hyperreactive. Observations from therapeutic studies of allergic rhinitis using antihistamines, intranasal corticosteroids, and immunotherapy, and how effective control of allergic rhinitis improves control of the symptoms of asthma and the dynamics of the lower airway will be discussed. The role of acute and chronic sinusitis, a common consequence of poorly controlled allergic rhinitis, in both contributing to poor control of chronic asthma and causing acute exacerbations will also be elucidated. Finally, the importance of humanistic outcomes measures in understanding the impact of both diseases and how they relate to each other in causing morbidity will be explained.
1. Centers for Disease Control and Prevention. CDC surveillance summaries: April 24, 1998. MMWR. 1998;47(No. SS-1).
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3. Asher MI, Keil U, Anderson HR, et al. International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods. Eur Respir J. 1995;8:483-491.
4. Settipane RJ, Hagy GW, Settipane GA. Long-term risk factors for developing asthma and allergic rhinitis: a 23-year follow-up study of college students. Allergy Proceedings. 1994;15:21-25.
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11. Bishop W. Sinus disease. The Journal-Lancet. 1920;XL:157-162.