Is headache related to asthma, hay fever, and chronic bronchitis? The Head-HUNT study

Objectives.-To examine the relationship between migraine and nonmigrainous headache and asthma, hay fever, and chronic bronchitis in a large cross-sectional population-based study. Background.-Associations between prevalence of migraine and asthma or allergy have been demonstrated in clinic-based and epidemiologic studies whereas studies on chronic bronchitis are scarce. Methods.-A total of 51,383 subjects completed a headache questionnaire and constituted the "Head-HUNT" Study. Of these 50,401 (98.1%) answered the questions about asthma and chronic bronchitis, and 47,029 (91.5%) answered the question about hay fever. Associations were assessed in multivariate analyses, estimating prevalence odds ratios (ORs) with 95% confidence intervals (CI). Results.-Both migraine and nonmigrainous headache were approximately 1.5 times more likely among those with current asthma, asthma related symptoms, hay fever, and chronic bronchitis than those without. The association increased with increasing headache frequency. Conclusions.-This large questionnaire-based study confirms that migraine and other headaches are associated with respiratory and allergic disorders. The magnitude of the association between headache and asthma, hay fever, and chronic bronchitis tended to be in the same order. Headache frequency seems to have a greater impact on the association with respiratory or allergic conditions than headache diagnoses. Whether it is a causal relationship is uncertain, but the results underline the importance of considering comorbid disorders among patients with frequent headache.