The treatment of allergic rhinitis with immunotherapy: A review of 1,000 cases.
We conducted a 10-year retrospective chart review of 1,000 immunotherapy-treated patients to evaluate the efficacy and safety of serial dilution quantitative intradermal testing in the management of allergic rhinitis. Three months after the initiation of immunotherapy, these patients had been assessed to ascertain whether or not they had experienced any overall improvement in their initial symptoms. Also included in this evaluation were determinations of each patient's use of medications as well as the incidence of adverse reactions to treatment and recurrent sinus infections. We found that 860 patients had achieved complete relief of their symptoms and required no other treatment; the remaining 140 patients experienced a partial improvement and continued to use pharmacotherapy to control breakthrough symptoms. During skin testing, only one patient experienced a systemic reaction, which responded to subcutaneous epinephrine. There were no deaths. We conclude that serial dilution quantitative intradermal testi ng is safe and that quantification of skin reactivity in evaluating and treating allergic rhinitis with immunotherapy is completely effective in the vast majority of patients.
Allergic rhinitis is the fifth most common chronic condition in the United States, affecting an estimated 36 million Americans. [1,2] Therefore, ensuring the efficacy and safety of skin testing in these patients is of extreme importance.
Interventional modalities for patients with allergic rhinitis include environmental control, immunotherapy, and treatment with pharmacologic agents such as decongestants, antihistamines, leukotriene inhibitors, and other mediator drugs. Skin testing is the best-established and most sensitive indicator of allergic disease. Several techniques are used to identify pertinent antigens in the treatment of inhalant allergies. The goals of allergy testing and immunotherapy are to accurately identify and quantify each antigen to which the patient is allergic so that a therapeutic approach can be designed to provide symptom relief in a safe but expedient manner.
Patients and methods
We reviewed the charts of 1,000 consecutive patients who had been treated with immunotherapy for allergic rhinitis between 1989 and 1999. These patients had been initially managed with environmental control, pharmacotherapy, and surgery when indicated. When their symptoms persisted, they underwent further evaluation and treatment based on the results of serial dilution quantitative intradermal skin testing.
Three months after they had started immunotherapy, all patients were re-evaluated and their symptoms were reassessed. Also evaluated were their use of medications as well as the incidence of treatment-related adverse effects and recurrent sinus infections that necessitated medical management.
During the initial 3 months of treatment, these patients had undergone a total of 105,000 intradermal skin tests and had received a total of 21,600 allergy injections. Only one patient experienced a systemic reaction to testing (hives and wheezing), which responded to one dose of subcutaneous epinephrine.
Of the 1,000 patients who were evaluated, 860 had experienced a complete response to immunotherapy. The criteria for a complete response included the eradication of symptoms, the lack of a need for any allergy medication, and the absence of sinus infection. The other 140 patients experienced a partial improvement, and they continued to take pharmacotherapy to control breakthrough symptoms and infection.
Skin testing involves the introduction of specific antigens onto or into the skin through a skin prick or an intradermal inoculation. Scratch testing is no longer a recommended diagnostic procedure because it has been found to be insensitive and not reproducible, particularly in comparison with prick testing. 
The skin prick is the test of choice of most general allergists even though it has some significant shortcomings. First, there is no method of standardizing and quantifying the skin response. Second, the skin prick test does not determine the precise level of sensitivity for specific antigens. Finally, it misses low-sensitivity responses because it cannot detect allergic disease at sensitivities less than the concentration of the antigen placed. As a result, immunotherapy based on skin prick testing must be started at doses sufficiently diluted to minimize the possibility of a systemic reaction. Months to years might be needed before therapeutic levels are reached. Also, because antigen sensitivities vary, obtaining a therapy-limiting response from one antigen might be possible in some patients, while others receive far-from-optimal dosages.
Serial dilution quantitative intradermal testing, also referred to as skin endpoint titration (SET), is a modified intradermal test that uses specific antigen dilutions to establish the minimum amount of antigen required to produce a positive skin test, also referred to as the endpoint. SET differs from other skin tests in that it is designed to be primarily a quantitative rather than qualitative test of allergen sensitivity. It identifies the endpoint for each antigen by using 1:5 dilutions of the allergen that is being tested. The endpoint identifies not only which antigens the patient is allergic to, it also indicates the patient's level of sensitivity to them and thus provides a safe point from which the physician can initiate immunotherapy. The endpoint does not correlate with symptomatology, and it does not predict the maintenance dose of therapy.
Once the different antigens have been evaluated for reactivity in this manner, a treatment vial can be mixed that will include each clinically pertinent antigen at its individual endpoint concentration. There are several advantages to the SET method. First, it has the ability to deliver antigen at a concentration that is safe and yet close to the maximum tolerated level at the onset of treatment. As a result, it shortens the length of time needed to achieve symptom relief, and it provides a means of advancing each antigen according to its particular level of sensitivity. Therefore, the physician can avoid the chance that a particularly high-sensitivity antigen will cause a local or systemic reaction during dose escalation. Such a reaction would limit the progression of the entire series and delay the attainment of therapeutic levels of other important but less-sensitive antigens.
The importance of quantifying skin reactivity during the evaluation and immunotherapeutic treatment of allergic rhinitis cannot be overemphasized. Only those skin tests that can quantify the patient's sensitivity to each antigen can provide the information necessary to formulate an optimal treatment program. 
Our review of these 1,000 patients who had undergone immunotherapy based on SET testing indicates that SET is a safe technique, and its ability to quantify allergic sensitivity can maximize the potential that immunotherapy will be successful.
(1.) Nathan RA, Meltzer EO, Selner JC, Storms W. Prevalence of allergic rhinitis in the United States. J Allergy Clin Immunol 1997;99(Suppl):S804-8.
(2.) Collins JG. Prevalence of selected chronic conditions: United States, 1986-88. Vital and Health Statistics. Hyattsville, Md.: Public Health Service. U.S. Department of Health and Human Services publication PHS 93-1510, series 10, No. 182, 1993.
(3.) In vivo diagnostic testing and immunotherapy for allergy. Report 1, Part I, of the allergy panel. Council on Scientific Affairs. JAMA 1987;258:1363-7.
(4.) Nelson HS. Diagnostic procedures in allergy. I. Allergy skin testing. Ann Allergy 1983;51:411-8.
(5.) Cook PR. In vivo testing and immunotherapy. Current Opinion in Otolaryngology--Head and Neck Surgery 1994;2:l18-27.
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|Comment:||The treatment of allergic rhinitis with immunotherapy: A review of 1,000 cases.|
|Author:||Trevino, Richard J.|
|Publication:||Ear, Nose and Throat Journal|
|Article Type:||Brief Article|
|Date:||Aug 1, 2001|
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