Sublingual Immunotherapy for Grass Pollen Allergy In Children: A Systematic Review and Meta-Analysis

Background: Sublingual immunotherapy (SLIT) using grass pollen extracts is an attractive treatment option compared with subcutaneous immunotherapy (SCIT) for children suffering with the symptoms of seasonal allergic rhino-conjunctivitis, with or without asthma.  However, evidence for the efficacy of SLIT in children remains unclear.  The objective was to undertake a systematic review of the available literature to identify high quality paediatric studies of SLIT for grass pollen allergy to assess the safety and benefits of SLIT compared with standard medication alone.

Methods: MEDLINE, EMBASE, CINAHL, NHSEED, DARE and Cochrane were searched from 1^st Jan 2000 to June 2010.   A pre-specified inclusion criteria was used to select studies, which were assessed for the risk of bias using the Jadad scale. The outcomes of interest were data from the studies including the reduction of nasal, eye and chest symptoms, use of symptom relieving medication and safety.

Results: Nine studies met the inclusion criteria.  A narrative synthesis on the safety of SLIT found a high incidence of mild, adverse events.   Outcomes were pooled using Rev Man 5 and the random effects model.  Inter-study heterogeneity was measured using the I² statistic and was <70% in all meta-analyses. The reduction of total allergic rhino-conjunctivitis symptom scores indicated a small highly significant reduction with non-significant heterogeneity. (SMD -0.24, 95% CI -0.38 to -0.11 P= 0.0005), (I² 15% P= 0.32).   The reduction in total relief medication use scores compared to placebo was non-significant.  (SMD-0.25 CI -0.50, 0.01, P= 0.06). I²   67% (P=0.006).

Conclusions: SLIT has a small benefit on symptoms but does not demonstrate a significant reduction in medication use. This justifies current SLIT use in paediatric allergy in the UK where availability is limited to children who remain symptomatic despite having proven concordance using optimised symptom relieving medication and children in whom SCIT is contra-indicated.