Subcutaneous immunotherapy and pharmacotherapy in seasonal allergic rhinitis: A comparison based on meta-analyses

Background

Allergen-specific subcutaneous immunotherapy (SCIT) of seasonal allergic rhinitis (SAR) is usually considered a “second-line,” slow-acting, disease-modifying treatment.

Objective

We sought to test whether SCIT is as effective as antisymptomatic treatment in the control of symptoms in patients with SAR in the first year of treatment.

Methods

We reviewed meta-analyses with 5 or more randomized, double-blind, placebo-controlled trials of SCIT or antisymptomatic treatment in patients with SAR. We then selected trials measuring the total nasal symptom score (TNSS), the total symptom score (TSS), or both during the first pollen season after treatment initiation. Efficacy was determined as the percentage reduction in TSSs and TNSSs obtained with active treatment compared with placebo (relative clinical impact [RCI]) and the standardized mean difference (SMD) of treatment verses placebo (effect size [ES]).

Results

The weighted mean RCI of SCIT on TNSSs (−34.7% ± 6.8%) was higher than those of mometasone (−31.7% ± 16.7%, P < .00001) and montelukast (−6.3% ± 3.0%, P < .00001). The weighted mean RCI of SCIT on TSSs (−32.9% ± 12.7%) was higher than that of desloratadine (−12.0% ± 5.1%, P < .00001). The overall ES of SCIT in terms of TNSSs (SMD, −0.94; 95% CI, −1.45 to −0.43) was similar to that of mometasone (SMD, −0.47; 95% CI, −0.63 to −0.32; P > .05) and higher than that of montelukast (SMD, −0.24; 95% CI, −0.33 to −0.16; P < .05). The overall ES of SCIT in terms of TSSs (SMD, −0.86; 95% CI, −1.17 to −0.55) was comparable with that of desloratadine (SMD, −1.00; 95% CI, −1.68 to −0.32; P > .05).

Conclusions

Our data provide indirect but consistent evidence that SCIT is at least as potent as pharmacotherapy in controlling the symptoms of SAR as early as the first season of treatment.

Key words: Seasonal allergic rhinitis, allergen-specific immunotherapy, allergen-specific subcutaneous immunotherapy, nasal corticosteroids, antihistamines, leukotriene antagonists

Abbreviations used: ES, Effect size, LA, Leukotriene antagonist, MoE, Magnitude of efficacy, RCI, Relative clinical impact, SAR, Seasonal allergic rhinitis, SCIT, Allergen-specific subcutaneous immunotherapy, SIT, Allergen-specific immunotherapy, SMD, Standardized mean difference, TNSS, Total nasal symptom score, TSS, Total symptom score, WAO, World Allergy Organization