title: Hypothesis: decreased use of pediatric aspirin has contributed to the increasing prevalence of childhood asthma.
abstract: BACKGROUND
  The prevalence of asthma, atopic eczema, and allergic rhinitis has increased over the last three decades in Western countries. Speculation on the causes of this trend have focused on changes in environmental factors. We hypothesize that the decreased use of aspirin in favor of acetaminophen, due to the association of aspirin with Reye's syndrome during febrile respiratory infections, may be contributing to these trends in the United States.
  
  
  METHODS
  A detailed literature search was conducted utilizing Medline. Studies considered relevant and important involving both humans and animals in English language were used.
  
  
  OBJECTIVE
  In the United States, the documented prevalence of childhood asthma has increased since 1970, but the rate of this increase accelerated upward beginning in the early 1980s when the use of pediatric aspirin decreased. During the resolution of common respiratory viral infections, prostaglandin E2 (PGE2) is produced through the actions of cyclooxygenase-2 (COX-2). Aspirin, but not acetaminophen, inhibits COX-2 activity. As PGE2 promotes TH2 and inhibits THI type cytokine generation, we hypothesize that the decreased use of aspirin may be a factor in facilitating allergic sensitization and asthma by augmenting the relative TH1/TH2 cytokine imbalance in genetically predisposed children.
  
  
  CONCLUSIONS
  We have presented an hypothesis based upon epidemiologic trends, known biologic effects of cytokines and PGE2 on allergic sensitization, and a potentially relevant pharmacologic effect of aspirin to explain a component of the increasing prevalence of childhood asthma in the United States. We suggest this theory be examined further in animal models as well as in other countries where the prevalence of childhood asthma is increasing.
authors.affiliation: Allergy Diagnostic, Beachwood, Ohio 44122, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Varner
authors.forename: W W
authors.initials: WW
authors.lastname: Busse
authors.forename: R F
authors.initials: RF
authors.lastname: Lemanske
mesh_terms: D000818:Animals; D001241:Aspirin / Q000009:adverse effects*; D001249:Asthma / Q000139:chemically induced* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D015995:Prevalence; D014481:United States
chemical_list: D001241:Aspirin