1. For patients with moderate to severe seasonal allergic rhinitis, 2 years of sublingual grass pollen immunotherapy was not significantly different than placebo at improving nasal response to allergen challenge at 3-year follow-up.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Allergic rhinitis has major effects on quality of life, sleep, and work and school performance. While antihistamines and topical nasal corticosteroids can be effective, many people do not respond sufficiently with these therapies. Grass pollen immunotherapy, both subcutaneous and sublingual, has emerged as an option that may alter the underlying course of the disease when given for 3 years. The purpose of this study was to determine whether only 2 years of sublingual immunotherapy could reduce symptoms after a nasal allergen challenge. A total of 106 adult patients at Imperial College of London with moderate to severe seasonal allergic rhinitis were randomized to 2 years of sublingual immunotherapy with placebo injections, subcutaneous immunotherapy with placebo tablets, or placebo injections and tablets. At 3 years after treatment initiation (1 year after treatment was discontinued), nasal allergen challenge was performed and total nasal symptoms scores (TNSS) were assessed, with 0 being the best score and 12 being the worst. The mean TNSS score for the sublingual immunotherapy group improved from 6.36 pretreatment to 4.73 at 3 years, whereas the placebo group’s score improved from 6.06 pretreatment to 4.81 at 3 years. The between-group difference was not significant.
Overall, this study suggests that for patients with moderate to severe seasonal allergic rhinitis, sublingual immunotherapy given for 2 years may not be effective at reducing symptoms. However, this study was not designed to compare 2 vs. 3 years of sublingual immunotherapy or sublingual vs. subcutaneous immunotherapy.
Relevant Reading: Long-Term Clinical Efficacy of Grass-Pollen Immunotherapy
In-Depth [randomized controlled trial]: This was a randomized, double-blind, placebo-controlled single-center trial conducted from 2011-2015. The study enrolled 106 adult patients with a minimum 2-year clinical history of moderate to severe seasonal allergic rhinitis. Patients were randomized to 2 years of sublingual immunotherapy (daily tablets containing major allergen Phleum p 5) with monthly placebo injections, subcutaneous immunotherapy (monthly injections with Phleum p 5) with daily placebo tablets, or matched double placebo (both injections and tablets). The nasal allergen challenge was performed and TNSS scores were obtained before treatment, at 1 and 2 years of treatment, and at 3 years (1 year after treatment was discontinued). The primary outcome was TNSS comparing sublingual immunotherapy vs. placebo at 3 years with subcutaneous immunotherapy as the positive control.
The study was not powered to compare sublingual vs. subcutaneous immunotherapy. The mean TNSS score for the sublingual immunotherapy group improved from 6.36 pretreatment (CI95% 5.76-6.96) to 4.73 (CI95% 3.97-5.48) at 3 years, whereas the placebo group’s score improved from 6.06 pretreatment (CI95% 5.23-6.88) to 4.81 (CI95% 3.97-5.65) at 3 years. The between-group difference, adjusted for baseline, was -0.18 (CI95% -1.25 to 0.90, p = 0.75), which was not significant. No serious treatment-related adverse events were recorded.
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