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

BackgroundSpecific 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. MethodsWe searched databases, ongoing clinical trials registers, and conference proceedings up to July 2015. Randomized controlled trials (RCTs) of SIT using standardized allergen extracts, compared with placebo/control, for treating AE in patients with allergic sensitization were eligible. ResultsWe identified 12 eligible trials with 733 participants. Interventions included subcutaneous (six trials), sublingual (four 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 nonblinding 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); and 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, for example investigator-rated improvement in eczema severity RR 1.48 (95% CI 1.16, 1.88; six trials, 262 participants). We found no evidence of adverse effects. The overall quality of evidence was low. ConclusionWe found no consistent evidence that SIT is effective for treating AE, but due to the low quality of evidence further research is needed to establish whether SIT has a role in AE treatment.