A treatment option review for allergic rhinitis and asthma
“Ah-choo! Ah-choo!†Those are the sneezes shared across 50 million allergy sufferers in the United States annually, leading to a decrease in productivity and sleep as well as a poor quality of life.1 Among 26 million Americans with asthma, 60% have allergen triggers for their asthma.Â
Many patients try over-the-counter allergy medications, including intranasal steroid sprays, antihistamine oral tablets, antihistamine eye drops and decongestants. Most patients respond to over-the-counter medications, but some respond poorly usually due to lack of adherence or adverse side effects.
Annually, 12 million physician office visits have allergic rhinitis as the primary diagnosis, and 10 million visits are due to asthma.2Â Patients are seeking better options for their allergic rhinitis, including longer-lasting treatments for their chronic allergic diseases. Aeroallergen immunotherapy is an option for moderate to severe allergic rhinitis/allergic asthma patients who have failed antiallergic drugs or have adverse side effects from medical therapy.Â
Aeroallergen subcutaneous immunotherapy (SCIT) uses high-dose standardized vaccines (5-20mcg of the major allergen in monthly maintenance injections) to shift from Th2 inflammation toward Th1 inflammation and induces a generation of suppressive regulatory cells. This decreases various interleukins (IL4, IL5,IL9,IL13) and eotaxins resulting in a decrease in mast cells, basophils and eosinophils in the mucosa.3 Therapy is initiated with a low-dose allergen that is advanced weekly until high dose concentration is achieved over the course of several weeks to months. This high dose is considered the maintenance dose. The maintenance dose is then given monthly for 3-5 years, providing long-lasting remission.Â
SCIT has been the mode of treatment for allergy patients since the early 1900s. Initially described by Noon from England in 1911, the treatment of hay fever with progressive injected doses of timothy grass pollen extract resulted in improved symptoms. This process was soon followed by Americans in the Eastern United States with similar treatment with ragweed for hay fever symptoms resembling Noon’s hay fever symptoms in England, except symptoms were noted to be later in the year.
Over the first 80 years, subcutaneous allergen immunotherapy was the main treatment program for moderate to severe allergic rhinitis. During this time, subcutaneous immunotherapy evolved from the treatment of one allergen to multiple allergens, and the FDA started standardization of allergens including cat, ragweed, grass and dust mites. Subcutaneous allergen immunotherapy provides many benefits for the patients, including a decreased dependence on oral allergy medications, decreased long-term cost, treatment of the underlying cause of the allergy, treating more than one allergen at a time and long-term allergy relief; disadvantages include a higher up-front cost, local reactions and possible anaphylaxis (rare), and it requires a time commitment for in-office visits (30-minute wait time).Â
Despite the benefits of subcutaneous allergen immunotherapy, compliance and persistence of therapy have been poor due to its lack of convenience. In contrast to subcutaneous immunotherapy, sublingual immunotherapy (SLIT) has proven safe to be administered at home. SLIT began in Europe in liquid extract form and has progressed to tablet form for grass, ragweed and house dust mites.Â
The tablet form of SLIT is newer and was first approved by the FDA in 2014. The immunologic mechanism in SLIT is thought to be the same as SCIT, but the efficacy is lower in SLIT than SCIT.4Â SLIT therapy involves holding either drops of the allergen extract or a tablet of allergen under the tongue for 2 minutes before swallowing and progressing daily to a maintenance dose that is continued daily for the course of 3 years. It can be taken continuously for 3 years or 2-4 months before the offending allergy season starts.Â
Benefits of SLIT therapy include a decreased dependence on oral allergy medications, decreased long-term cost, treatment of the underlying cause of the allergy, treating more than one allergen at a time, providing long-term allergy relief and the convenience of at-home self-administration. Disadvantages include local side effects including oropharyngeal itching and swelling of tongue and mouth; lower efficacy compared to SCIT; efficacy studies are mainly with monotherapy5, adherence is more difficult to monitor and evidence base in children is less convincing.Â
In summary, both modalities of allergen immunotherapy, either subcutaneous or sublingual, can offer allergy sufferers significant relief with long-term remission. An allergist can help identify the appropriate candidate by conducting a thorough history, physical and allergy testing to identify the allergens, then select the best treatment plan with shared decision-making between patient and allergist to ensure the success of treatment selected.Â
References
1. Summary health statistics: National Health Interview Survey, 2018. National Center for Health Statistics. Table A-2b,A-2c. 2018
2. National Ambulatory Medical Care Survey: 2016 National Summary Tables, table 15Â pdf icon
3. Shamji M, Durham S. Mechanisms of allergen immunotherapy for inhaled allergens and predictive biomarkers. J Allergy Clin Immunol. 2017;140:1485–1498.
4.Wilson D, Lima M, Durham S. Sublingual immunotherapy for allergic rhinitis: systematic review and meta-analysis. Allergy 2005;60:4-12.
5.Nelson HS, Makatsori M, Calderon MA. Subcutaneous immunotherapy and sublingual immunotherapy. Immunol, Allergy Clinics N Am. 2016;36:13–24.
