OBJECTIVES

Allergic rhinitis is highly prevalent in North America, affecting 20 to 40 percent of the population. Nearly 9 percent of Americans suffer from asthma, with more than half having evidence of atopy. This comparative effectiveness review describes the effectiveness and safety of subcutaneous immunotherapy and sublingual immunotherapy (off-label use of subcutaneous-aqueous allergens for sublingual desensitization) compared with other therapies for treatment of allergic rhinoconjunctivitis and asthma.

DATA SOURCES

We searched the MEDLINE, Embase, LILACS, and CENTRAL databases from the beginning of each database through May 21, 2012.

REVIEW METHODS

Two reviewers independently selected randomized controlled trials according to established study inclusion criteria. Disagreements were resolved by consensus. Paired reviewers assessed the risk of bias of each study and extracted details about the population, intervention(s), and outcomes of interest. The results were summarized by immunotherapy type (sublingual or subcutaneous), allergen, and outcomes. Studies exclusively enrolling children were reviewed separately. The strength of the body of evidence was graded and summarized.

RESULTS

We included 74 references that investigated the efficacy and safety of subcutaneous immunotherapy, 60 studies that investigated the efficacy and safety of sublingual immunotherapy, and 8 studies that compared the two modes of delivery. All 142 studies were randomized controlled studies. The majority of studies were at medium risk of bias due to design choices. The strength of evidence is high that subcutaneous immunotherapy reduces asthma symptoms, rhinitis symptoms, conjunctivitis symptoms, asthma medication use, asthma plus rhinoconjunctivitis medication use, and rhinoconjunctivitis-specific quality of life. The strength of evidence is moderate that subcutaneous immunotherapy reduces rhinoconjunctivitis medication use, relative to usual care, which includes pharmacotherapy. Likewise, the strength of evidence is high that sublingual immunotherapy reduces asthma symptoms. The strength of evidence is moderate that sublingual immunotherapy reduces rhinitis/rhinoconjunctivitis symptoms, combined symptom scores, conjunctivitis symptoms, and medication useusage relative to usual care, and improves allergy-specific quality of life. In studies comparing subcutaneous with sublingual immunotherapy, strength of evidence supporting the superiority of subcutaneous immunotherapy for reducing allergic rhinitis and conjunctivitis symptoms, and the superiority of sublingual immunotherapy for reducing medication use, is low. We identified 13 pediatric studies of subcutaneous immunotherapy, 18 pediatric studies of sublingual immunotherapy, and 3 pediatric studies comparing subcutaneous and sublingual immunotherapy. The strength of evidence is moderate that subcutaneous immunotherapy reduces asthma symptoms and rhinitis symptoms in comparison to usual care. The strength of evidence is low that subcutaneous immunotherapy reduces conjunctivitis symptoms, medication scores, combined symptom-medication scores, or improves quality of life relative to usual care. The strength of evidence is high that sublingual immunotherapy reduces asthma symptoms, and moderate that it reduces rhinitis/rhinoconjunctivitis symptoms, combined asthma plus rhinitis/rhinoconjunctivitis symptoms, conjunctivitis symptoms, and decreases medication use. While local reactions were frequent with both treatment regimens, there were rare reports of anaphylaxis in the subcutaneous immunotherapy studies, and no anaphylaxis reported in the sublingual immunotherapy studies.

CONCLUSIONS

With some variation across outcomes, the overall body of evidence consistently provides moderate to high support for the effectiveness and safety of both subcutaneous and sublingual immunotherapy for the treatment of allergic rhinitis and asthma. The evidence to support the use of immunotherapy in children is somewhat weaker than the evidence supporting its use in adults. The superiority of one route of administration over the other is not known.