Saturday, September 26, 2009

The Safety and Efficacy of Allergen Immunotherapy

Every time a person decides to begin allergen immunotherapy (IT) for allergic rhinitis (commonly referred to as hay fever), they should ask about it's safety and benefits. This topic has been reviewed many times in the medical literature by objective researchers. The Cochrane Database of Systemic Reviews published their findings on 1/24/07 here.

Immunotherapy is safe when given to properly selected patients in the proper setting. Properly selected patients means they have at least moderately severe allergic rhinitis, that has been confirmed by either blood tests (RAST) or allergy skin tests. The proper setting is a physician's office with injections being given by trained personnel and having both the necessary backup equipment and a physician present in the event of a reaction. Both international societies of allergy based in the U.S., the ACAAI and the AAAAI, endorse this as what should be the standard of care in the U.S. I also endorse this and assure our patients that we are in 100% compliance with this. The Cochrane Review "found no long-term consequences from adverse events and no fatalities".

A 2003 Cochrane Review concluded that immunotherapy is effective at reducing the symptoms and signs of allergic rhinitis and medication use when given to properly selected patients for the appropriate length of time. The proper patients were described above. The appropriate length of time is 3 to 5 years for about 85% of patients. Less than 5% get long lasting and significant relief in less than 3 years, but I wish everyone's immune system would respond this quickly to IT. About 10% of patients find that IT continues to benefit them after more than 5 years. I have a discussion with those patients annually about whether or not IT should be continued. Less medication use becomes a significant long-term savings as the cost of medications and medication copays continue to rise.

Immunotherapy is also effective at reducing the symptoms and signs of allergic asthma and medication use. The effectiveness in meta-analysis, that is groups of studies analyzed together, has been estimated at about 70% for mild, or medium, or high. For unclear reasons, about 30% of patients do not benefit. This is based on patients that have completed a 3 to 5 year course of IT. In my experience, factors that contribute to the poor response include: lack of compliance with medications and avoidance measures, prescence of tobacco smoke at home, lack of routine injections, and lack of high dose allergens in the extracts. In my offices, we routinely try to give high dose allergens in IT. If your office does not give high doses of allergens, then the efficacy rate will be significantly reduced, possibly to the point of showing no benefit. I am a board certified, in 1993 and re-certified in 2003, physician that has completed a two year training period focusing exclusively on all aspects of the diagnosis and treatment of allergic dieseases. These are facts that you should consider when you decide to start, continue, or discontinue allergen immunotherapy.

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