Osmophobia and Headaches in Primary Care: Prevalence, Associated Factors, and Importance in Diagnosing Migraine.

OBJECTIVES The aims of this study were to investigate the prevalence of osmophobia among primary headaches, evaluate the association between osmophobia and the characteristics of patients and their headaches, and assess the usefulness of this symptom for diagnosing migraine. METHODS This was a cross-sectional study in a primary care unit. Patients who consecutively sought medical attendance in a primary care unit were asked about headaches (convenience sample). Those who reported having had at least 1 episode of headache during the last 12 months were interviewed. Semi-structured interview, the Headache Impact Test, and the Hospital Anxiety and Depression Scale were used. RESULTS Two hundred thirty-five patients had headaches, 147 patients had migraine (53% of them had osmophobia), and 87 had tension-type headache (11.5% of them had osmophobia), and 1 patient had an unclassifiable headache. Among the headache patients, those with migraine and more years of headache history presented significantly more osmophobia (multivariate logistic regression).The sensitivity and specificity of osmophobia for establishing a diagnosis of migraine were 53.1% and 87.5%. The positive predictive value and negative predictive value were 87.6% and 52.7%. CONCLUSION We found high prevalence of osmophobia among migraine patients, and this complaint is useful in making the diagnosis of migraine in primary care. Osmophobia is associated with migraine and more years of headache history.