title: Allergic rhinitis: evidence for impact on asthma.
abstract: BACKGROUND
  This paper reviews the current evidence indicating that comorbid allergic rhinitis may have clinically relevant effects on asthma.
  
  
  CONCLUSIONS
  Allergic rhinitis is very common in patients with asthma, with a reported prevalence of up to 100% in those with allergic asthma. While the temporal relation of allergic rhinitis and asthma diagnoses can be variable, the diagnosis of allergic rhinitis often precedes that of asthma. Rhinitis is an independent risk factor for the subsequent development of asthma in both atopic and nonatopic individuals. Controlled studies have provided conflicting results regarding the benefits for asthma symptoms of treating comorbid allergic rhinitis with intranasal corticosteroids. Effects of other treatments for comorbid allergic rhinitis, including antihistamines, allergen immunotherapy, systemic anti-IgE therapy, and antileukotriene agents, have been examined in a limited number of studies; anti-IgE therapy and antileukotriene agents such as the leukotriene receptor antagonists have benefits for treating both allergic rhinitis and asthma. Results of observational studies indicate that treating comorbid allergic rhinitis results in a lowered risk of asthma-related hospitalizations and emergency visits. Results of several retrospective database studies in the United States and in Europe indicate that, for patients with asthma, the presence of comorbid allergic rhinitis is associated with higher total annual medical costs, greater prescribing frequency of asthma-related medications, as well as increased likelihood of asthma-related hospital admissions and emergency visits. There is therefore evidence suggesting that comorbid allergic rhinitis is a marker for more difficult to control asthma and worsened asthma outcomes.
  
  
  CONCLUSIONS
  These findings highlight the potential for improving asthma outcomes by following a combined therapeutic approach to comorbid allergic rhinitis and asthma rather than targeting each condition separately.
authors.affiliation: Department of General Practice and Primary Care, University of Aberdeen, Foresterhill Health Centre, Westburn Road, Aberdeen AB25 2AY, UK. drmike.thomas@btinternet.com
authors.forename: Mike
authors.initials: M
authors.lastname: Thomas
mesh_terms: D000328:Adult; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000453:epidemiology* / Q000628:therapy*; D015984:Causality; D002648:Child; D015897:Comorbidity; D004359:Drug Therapy, Combination; D014943:Global Health; D006634:Histamine H1 Antagonists / Q000627:therapeutic use; D006801:Humans; D020024:Leukotriene Antagonists / Q000627:therapeutic use; D010043:Outcome and Process Assessment, Health Care; D015995:Prevalence; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology* / Q000628:therapy*; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology* / Q000628:therapy*
chemical_list: D018927:Anti-Asthmatic Agents; D006634:Histamine H1 Antagonists; D020024:Leukotriene Antagonists