Allergen immunotherapy for allergic rhinoconjunctivitis : a systematic review and meta-analysis

BACKGROUND: The European Academy of Allergy and Clinical Immunology (EAACI) is in the process of developing Guidelines on Allergen Immunotherapy (AIT) for Allergic Rhinoconjunctivitis. In order to inform the development of clinical recommendations, we undertook a systematic review to assess the effectiveness, cost-effectiveness and safety of AIT in the management of allergic rhinoconjunctivitis METHODS: We searched 15 international biomedical databases for published, in progress and unpublished evidence. Studies were independently screened by two reviewers against pre-defined eligibility criteria and critically appraised using established instruments. Our primary outcomes of interest were symptom, medication and combined symptom and medication scores. Secondary outcomes of interest included cost-effectiveness and safety. Data were descriptively summarized and then quantitatively synthesized using random-effects meta-analyses. RESULTS: We identified 5932 studies of which 160 studies satisfied our eligibility criteria. There was a substantial body of evidence demonstrating significant reductions in standardized mean differences (SMD) of symptom (SMD -0.53, 95%CI -0.63, -0.42), medication (SMD -0.37, 95%CI -0.49, -0.26) and combined symptom and medication (SMD -0.49, 95%CI -0.69, -0.30) scores whilst on treatment that were robust to pre-specified sensitivity analyses. There was in comparison a more modest body of evidence on effectiveness post-discontinuation of AIT, this suggesting a benefit in relation to symptom scores. CONCLUSIONS: AIT is effective in improving symptom, medication and combined symptom and medication scores in patients with allergic rhinoconjunctivitis whilst on treatment, and there is some evidence suggesting that these benefits are maintained in relation to symptom scores after discontinuation of therapy. This article is protected by copyright. All rights reserved.