Allergy and Immunotherapy: Are They Related to Migraine Headache?

Introduction.- Several studies have reported that migraine headaches are more common in patients with allergic rhinitis and that immunotherapy decreases the frequency of headache in atopic headache sufferers. Objective.- To determine if the degree of allergic sensitization and the administration of immunotherapy are associated with the prevalence, frequency, and disability of migraine headache in patients with allergic rhinitis. Methods.- Consecutive patients between the ages of 18-65 presenting to an allergy practice that received a diagnosis of an allergic rhinitis subtype (eg, allergic or mixed rhinitis) were enrolled in this study. All participants underwent allergy testing as well as a structured verbal headache diagnostic interview to ascertain the clinical characteristics of each headache type. Those reporting headaches were later assigned a headache diagnosis by a headache specialist blinded to the rhinitis diagnosis based on 2004 International Classification Headache Disorders-2 (ICHD-2) diagnostic criteria. Migraine prevalence was defined as the percentage of patients with a diagnosis of migraine headache (ICHD-2 diagnoses 1.1-1.5). Migraine frequency represented the number of days per month with migraine headache self-reported during the headache interview and migraine disability was the number of days with disability obtained from the Migraine Disability Assessment questionnaire. Generalized linear models were used to analyze the migraine prevalence, frequency, and disability with the degree of allergic sensitization (percentage of positive allergy tests) and administration of immunotherapy as covariates. Patients were categorized into high (> 45% positiveallergy tests) and low (< 45% positive allergy tests) atopic groups based on the number of allergy tests that were positive for the frequency and disability analyses. Results.- A total of 536 patients (60% female, mean age 40.9 years) participated in the study. The prevalence of migraine was not associated with the degree of allergic sensitization, but there was a significant age/immunotherapy interaction (P < .02). Migraine headaches were less prevalent in the immunotherapy group than the nonimmunotherapy at ages < 40 years and more prevalent in the immunotherapy group at ages >= 40 years of age. In subjects < 45 years of age, increasing percentages of allergic sensitization were associated with a decreased frequency and disability of migraine headache in the low atopic group (risk ratios [RRs] of 0.80 [95% CI; 0.65, 0.99] and 0.81[95% CI; 0.68, 0.97]) while increasing percentages were associated with an increased frequency (not disability) in the high atopic group (RR = 1.60; [95% CI; 1.11, 2.29]). In subjects < 45 years of age, immunotherapy was associated with decreased migraine frequency and disability (RRs of 0.48 [95% CI; 0.28, 0.83] and 0.55 [95% CI; 0.35, 0.87]). In those > 45 years of age, there was no effect of degree of allergic sensitization or immunotherapy on the frequency and disability of migraine headache. Conclusions.- Our study suggests that the association of allergy with migraine headaches depends upon age, degree of allergic sensitization, administration of immunotherapy, and the type of headache outcome measure that are studied. Lower "degrees of atopy" are associated with less frequent and disabling migraine headaches in younger subjects while higher degrees were associated with more frequent migraines. The administration of immunotherapy is associated with a decreased prevalence, frequency, and disability of migraine headache in younger subjects.