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

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

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

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.

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.

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.