Specific allergen immunotherapy for the treatment of atopic eczema: a systematic review

Background: Specific allergen immunotherapy (SIT) is an effective allergy treatment, but it is unclear whether SIT is effective for atopic eczema (AE). We undertook a systematic review to assess SIT efficacy and safety for treating AE. Methods: We searched databases, ongoing clinical trials registers, and conference proceedings up to July 2015. Randomised-controlled trials (RCTs) of SIT using standardised allergen extracts, compared with placebo/control for treating AE in patients with allergic sensitisation were eligible. Results: We identified 12 eligible trials with 733 participants. Interventions included subcutaneous (6 trials), sublingual (4 trials), oral, or intradermal SIT in children/adults allergic to house dust mite (10 trials), grass pollen or other inhalants. Risk of bias was moderate, with high loss to follow-up and non-blinding as the main concerns. For our primary outcomes three studies (208 participants) reported no significant difference - patient-reported global disease severity improvement RR 0.75 (95%CI 0.45, 1.26); eczema symptoms mean difference -0.74 on a 20-point scale (95%CI -1.98, 0.50). Two studies (85 participants) reported a significant difference - SIT improved global disease severity RR 2.85 (95%CI 1.02, 7.96); and itch mean difference -4.20 on a 10-point scale (95%CI -3.69, -4.71). Meta-analysis was limited due to extreme statistical heterogeneity. For some secondary outcomes, meta-analyses showed benefits for SIT eg investigator-rated improvement in eczema severity RR 1.48 (95%CI 1.16, 1.88; 6 trials, 262 participants). We found no evidence of adverse effects. The overall quality of evidence was low