Network meta-analysis shows commercialized subcutaneous and sublingual grass products have comparable efficacy

Abstract

Background: Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) have been shown to effectively treat grass pollen allergies, although direct comparisons are sparse.

Objective: To estimate the relative efficacy of SLIT tablets compared with SCIT and SLIT drops in commercially available products though network meta-analysis.

Methods: A literature search of MEDLINE, Embase, and Cochrane Library publications. Randomized, double-blind clinical trials of SCIT, SLIT drops, and SLIT tablets for grass pollen were included. Bayesian network meta-analyses estimated the standardized mean difference (SMD) across 3 immunotherapy modalities on allergic rhinoconjunctivitis symptom and medication score data from publications or received from authors. Both fixed and random effects models were investigated.

Results: Thirty-seven studies were included in meta-analyses for symptom scores and 31 studies for medication scores. In the random effects model, SCIT and SLIT tablets were significantly different from placebo for symptom scores: SMDs (95% CI) of -0.32 (-0.45 to -0.18) and -0.32 (-0.41 to -0.23), respectively. No significant difference was identified for SLIT drops compared with placebo (SMD, -0.17; -0.37 to 0.04). For medication scores, significant differences compared with placebo were observed for SCIT (SMD, -0.33; 95% CI, -0.52 to -0.13), SLIT tablets (SMD, -0.23; 95% CI, -0.29 to -0.17), and SLIT drops (SMD, -0.44; 95% CI, -0.83 to -0.06). Network meta-analysis revealed no significant differences in SMDs (95% credible interval) for symptom scores (0.0145 [-0.19 to 0.23]) or medication scores (0.133 [-0.31 to 0.57]) between SLIT tablets and SCIT, or for symptom scores (-0.175 [-0.37 to 0.02]) and medication scores (0.188 [-0.18 to 0.56]) between SLIT tablets and SLIT drops.

Conclusions: The comparisons for grass pollen immunotherapy products commercialized in at least 1 country indicate comparable reductions in allergic rhinoconjunctivitis symptoms and supplemental medication use for SLIT tablets and SCIT in the first pollen season.

Keywords: Allergen immunotherapy; grass pollen; immunotherapy; meta-analysis; subcutaneous immunotherapy; sublingual immunotherapy.