The Effect of Pollen Season on Subcutaneous Allergen Immunotherapy Reactions

Subcutaneous allergen immunotherapy (SCIT) is a widely used and effective treatment modality for allergic rhinoconjunctivitis and asthma. SCIT starts with a build-up phase during which a patient receives frequent, escalating doses of the allergens they are allergic to until they reach a predetermined maintenance dose. This is followed by a maintenance phase during which the allergen dose is kept constant and administered at greater intervals. Maximum clinical improvement is generally not seen until a patient is in the maintenance phase. Anecdotal evidence of possible reactions to SCIT administered during a patient's pollen season has led to dosage freezes during a patient's pollen season which extends the length of the build-up phase by many months. Prolonging the buildup phase increases the time required to obtain maximal benefit from SCIT, and at the same time, can decrease patient compliance with therapy due to the prolonged period of time when frequent injections are required. The aims of this study are to determine if adverse reactions to pollen SCIT are increased if doses are increased during pollen season. Specific Aim 1: To determine if escalating pollen SCIT doses during the pollen season is associated with an increased rate of immediate reactions in comparison to holding SCIT doses constant. Hypothesis: There will not be an increased rate of immediate reactions to SCIT in build up phase received during the pollen season in comparison to SCIT held for pollen season. Strategy: In a prospective trial, 245 subjects will be randomized to receive monthly (doses held constant) or weekly (doses built up) injections. Rate of immediate local and systemic reactions per injection will be compared between the two groups. Specific Aim 2: To determine if escalating pollen SCIT doses during the pollen season is associated with an increased rate of delayed reactions in comparison to holding SCIT doses constant. Hypothesis: There will not be an increased rate of delayed reactions to SCIT in build up phase received during the pollen season in comparison to SCIT held for pollen season. Strategy: In a prospective trial, 245 subjects will be randomized to receive monthly (doses held constant) or weekly (doses built up) injections. Rate of delayed reactions per injection will be compared between the two groups. BACKGROUND AND SIGNIFICANCE Immunotherapy is one of the most effective therapies for allergic rhinoconjunctivitis, but the protocol dosing during pollen season is based on limited data. Immunotherapy is given in increasing dosage during the build up phase in order to build tolerance. After the build up phase, there is a maintenance phase that is used for the remainder of therapy. At this time, there is little data to support the common practice of not increasing the dosage of immunotherapy during pollen seasons. The recent allergen immunotherapy practice parameter references 2 articles that have noted no increased systemic reactions to SCIT during pollen season. , In one prospective study, it was concluded that there was no direct correlation of reactions to SCIT and pollen season.3 They did note a correlation between the mean monthly mold counts in August to October and the rate of systemic reactions. The other study referenced is a prospective study which did not observe a statistically significant difference in the rate of systemic reactions to grass or ragweed pollen during their respective pollen seasons.4 However, the conclusions of these studies are conflicted by another study which consists of surveys retrospectively sent to members of the American Academy of Allergy Asthma and Immunology. The surveys in this study identified 46% of near fatal reactions to SCIT as occurring during peak allergy season. Though the immunotherapy standard parameters are not defining pollen season as a contraindication, we will consider it more that minimal risk for this study. It is still common practice to stop the buildup phase and not escalate SCIT dosing during pollen season due to the conflicting available data and limitations in study design of many of the studies (retrospective, questionnaire based). A further look into SCIT dosing during pollen season will allow for more standardized practice and potentially improved patient outcomes.