Economic Impact and Quality-of-Life Burden of Allergic Rhinitis

William F. Schoenwetter; Leon Dupclay, Jr; Sireesh Appajosyula; Marc F. Botteman; Chris L. Pashos

Disclosures

Curr Med Res Opin. 2004;20(3) 

In This Article

Prevalence

In 1999, the reported prevalence of allergic rhinitis in young adults approximately 16-18 years of age was 23% in Great Britain, 26% in the United States, and 36% in Japan.[8] In the United States, allergic rhinitis ranks as the fifth most common chronic disease.[9] According to the Joint Task Force on the Diagnosis and Treatment of Rhinitis, this disease affects 20-40 million people in the United States annually, including 10%-30% of adults and up to 40% of children.[1] Only 10%-20% of US children with allergic rhinitis and asthma show a resolution of both diseases within 10 years of onset.[8] Further, at least 35.9 million Americans have symptoms closely associated with allergic rhinitis, and up to 79.5 million experience at least 7 days of undiagnosed nasal/ocular symptoms annually.[10]

The prevalence of allergic rhinitis seems to be increasing in the United Kingdom and in other countries worldwide, which may be due at least in part to improved reporting methods and growing patient awareness.[8] Direct-to-consumer advertising, access to the Internet and its health-related resources, television coverage of allergies and asthma, and educational efforts by managed care companies may have prompted increasing numbers of patients with allergic rhinitis to report their symptoms to their primary care practitioners.

In addition to an increase in the reporting of allergic rhinitis, the disease itself may be exhibiting an actual increase in prevalence. Possible causes for such an increase have not been definitively identified, but contributory factors may include a recent increase in airborne pollution; increases in dust mite populations in sealed or inadequately ventilated offices and homes with central heating and air conditioning; and the current trend toward more sedentary lifestyles. Other more controversial theories that attempt to explain the increased prevalence of allergic rhinitis over the last 40 years include the following[11]:

  • Changes in diet, antibiotic use, immunizations, and patterns of infection in childhood, leading to changes in the numbers of people with T-helper (Th) 2, rather than Th1 immune responses, as well as numbers of people who produce immunoglobulin (Ig) E antibodies to inhaled allergens.[11]

  • The 'hygiene hypothesis' associated with the greatly improved sanitation typical of a Western lifestyle, which is gaining credence.

The 'Hygiene Hypothesis'. The hygiene hypothesis, a theory that attempts to explain the increased prevalence of allergic rhinitis, proposes that because of improved sanitation, particularly in developed countries, infants and young children are not exposed to the large numbers of microorganisms (bacteria, viruses, fungi) required to develop normal immune defenses.[12] The critical period for developing long-lasting immunity is during the first 2 years of life. An immature or inappropriate immune system opens the way to allergen-induced, inflammatory airway diseases, such as allergic rhinitis. The hygiene hypothesis also links the development of allergic diseases to such factors as immunization with a variety of vaccines and the use of antibiotics in infants and young children.

Support for the hygiene hypothesis has been provided by epidemiologic studies conducted by Ring et al.[13] After the fall of the Berlin Wall, these authors conducted comparative epidemiologic studies over a 3-year period in various regions in East and West Germany. Data accrued included responses on yearly questionnaires and physical, dermatologic, allergologic, and exposure examinations in approximately 30 000 preschool children. 'Striking differences' were noted between regions, with higher prevalences of atopy (i.e., allergic rhinitis, asthma) and atopic sensitization (measured by skin prick and radioallergosorbent tests) in West Germany. These higher prevalences of allergic rhinitis and asthma were found to correlate significantly (odds ratio 1.7) with the higher education level of parents in West Germany, i.e., university versus elementary school. It was suggested that the 'psychological environment' created by the modern or western lifestyle of West Germans, with its emphasis on maintaining sanitary conditions, may have precluded the development of normal immunity and influenced the development of atopic sensitization and diseases.

The hygiene theory has gained support in several studies of farm children, or children growing up in an environment providing substantial exposure to farm animals, who appeared to develop significant protection against the development of atopy.[14,15,16,17,18] For instance, in one study of 84 families in southern Germany and Switzerland,[14] farm children exposed to high levels of endotoxin, which is found in the outer membrane of Gram-negative bacteria and which accumulates in stable dust, demonstrated a degree of immunity to the development of atopic disease not seen in control children of nonfarming families. A limitation of exposure studies such as these is that, although it is known that endotoxinis are associated with farm environments and that farming communities in general are associated with decreased risk of atopy, how individual members of a community are affected is an unknown. High levels of endotoxin exposure may be a surrogate for other aspects of exposure associated with a risk of atopy. However, studies have shown that exposure to other allergy-inducing substances found in stables (mold, for example), do not afford protection against the development of childhood wheezing and asthma.[19]

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