Effectiveness of subcutaneous immunotherapy for allergic rhinoconjunctivitis and asthma: a systematic review

To systematically review the effectiveness and safety of subcutaneous immunotherapy (SCIT) for treatment of allergic rhinoconjunctivitis and asthma, using formulations currently approved in the United States.

We searched the following databases up to May 21, 2012: MEDLINE, Embase, LILACS, and the Cochrane Central Register of Controlled Trials.

We included randomized controlled trials published in English comparing SCIT to placebo, pharmacotherapy, or other SCIT regimens that reported clinical outcomes of interest. Studies of adults or mixed age populations were included. Studies were excluded if the diagnosis of allergy and/or asthma was not confirmed with objective testing. Paired reviewers selected articles for inclusion and extracted data. We assessed the risk of bias for each study and graded the strength of evidence for each outcome as high, moderate, or low.

Sixty-one studies met our inclusion criteria. Majority of the studies (66%) evaluated single-allergen immunotherapy regimens. The literature provides high-grade evidence that SCIT reduces asthma symptoms, asthma medication usage, rhinitis/rhinoconjunctivitis symptoms, conjunctivitis symptoms, and rhinitis/rhinoconjunctivitis disease-specific quality of life in comparison to placebo or usual care. There is moderate evidence that SCIT decreases rhinitis/rhinoconjunctivitis medication usage. Respiratory reactions were the most common systemic reaction. There were few reports of anaphylaxis; no deaths were reported.

Generally moderate to strong evidence supports the effectiveness of SCIT for treatment of allergic rhinitis and asthma, particularly with single-allergen immunotherapy regimens. Adverse reactions to SCIT are common, but no deaths were reported in the included studies.