Among patients with moderate to severe seasonal allergic rhinitis, two years of immunotherapy tablets was not significantly different from placebo in improving nasal symptoms at 3-year follow-up, according to a study appearing in the February 14 issue of JAMA.
The prevalence of allergic rhinitis in the United States has been estimated at 15 percent based on physician diagnosis and at 30 percent based on self-reported nasal symptoms. Rhinitis has major effects on quality of life, sleep, and work and school performance.
Three years of continuous treatment with subcutaneous (injection) immunotherapy and sublingual (tablets) immunotherapy has been shown to improve symptoms for at least two years following discontinuation of treatment. It is unknown whether a shorter course of immunotherapy provides long-term benefits, while reducing overall costs, patient inconvenience, and adverse events.
Stephen R. Durham, M.D., of Imperial College London, and colleagues randomly assigned 106 adults with moderate to severe seasonal allergic rhinitis to receive two years of sublingual immunotherapy (n=36; daily tablets containing 15 ?g of major allergen Phleum p 5 and monthly placebo injections); subcutaneous immunotherapy (n=36; monthly injections containing 20 ?g of Phleum p 5 and daily placebo tablets); matched double-placebo (n=34). Nasal allergen challenge was performed before treatment, at one and two years of treatment, and at three years (1 year after treatment discontinuation).
Among 106 randomized participants, 92 completed the study at three years. The researchers found that treatment for two years with grass pollen sublingual immunotherapy was not sufficient to achieve an allergic response improvement at 3-year follow-up.
"International guidelines regarding immunotherapy recommend a minimum of 3 years of treatment with both delivery methods [subcutaneous, sublingual]. If a 2-year regimen had demonstrated long-term benefits in addition to efficacy, this could have represented cost savings in terms of clinical resources and improved convenience for the patient. Because this was not observed, clinicians should be advised to follow established guidelines that recommend at least 3 years treatment," the authors write.
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