Allergen immunotherapy for the treatment of allergic rhinitis and/or asthma: an umbrella review

Abstract

Background: Allergic rhinitis and asthma are important public health concerns, yet there is no consensus about the benefits and harms of allergen-specific immunotherapy to treat these conditions. We performed an umbrella review of systematic reviews summarizing the current evidence for the benefits and harms of subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT).

Methods: We searched MEDLINE, Embase, the Cochrane Library and the grey literature from Jan. 1, 2010 to Nov. 20, 2016 for systematic reviews of randomized controlled trials or prospectively controlled studies involving children or adults with allergic rhinitis or asthma. Outcomes were summarized narratively (benefits: total combined symptom-medication score, symptom score, medication score, disease-specific quality of life, adherence; harms: anaphylaxis, death, local and systemic reactions).

Results: Twenty-three systematic reviews were included. SCIT and SLIT were more effective than placebo for most outcomes. SCIT was better than SLIT at improving medication and symptom scores, with no differences in quality of life; however, data were limited for this comparison. Anaphylaxis and death were infrequently reported. Few reviews assessed benefits or harms among children.

Interpretation: Allergen immunotherapy appears to be effective among patients with allergic rhinitis and asthma. The safety of allergen immunotherapy is not conclusively established, although death and anaphylaxis appear to be rare. PROSPERO no.: CRD42015024590.

Figure 1

PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) diagram showing selection of included reviews. *The initial search results included studies on venom immunotherapy, which was subsequently determined to be outside the scope of this overview. Venom immunotherapy was assessed in the environmental scan portion of this drug class review (http://odprn.ca/wp-content/uploads/2016/02/Allergen-Immunotherapy_Environmental-Report_Oct-2-2015_FINAL.pdf).

Figure 2

Summary of benefits of subcutaneous (SCIT) and sublingual (SLIT) immunotherapy. The five contiguous circles correspond, respectively, to the 5 efficacy outcomes: total combined symptom-medication score, symptom score, medication score, disease-specific quality of life and adherence/discontinuation. A green circle indicates that immunotherapy is significantly better than placebo, a red circle indicates that immunotherapy is significantly worse than placebo, a grey circle indicates that there is no significant difference between immunotherapy and placebo, and a white circle indicates that the outcome was not available for analysis. In cases of immunotherapy versus immunotherapy, significance is reported relative to the first agent listed in the heading.