Accuracy of osmophobia in the differential diagnosis between migraine and tension-type headache

Our objective was to determine the accuracy parameters of osmophobia in the differential diagnosis between migraine and tension-type headache. Migraine or tension-type headache patients, diagnosed according to the criteria of the International Classification of Headache Disorders-II, were interviewed about osmophobia during the crisis and in the period between episodes. We studied 200 migraine patients and 200 tension-type headache patients. During the crisis, osmophobia occurred in 86.0% (172/200) of patients with migraine and 6.0% (12/200) of those with tension-type headache. In migraine, osmophobia was associated with photophobia and phonophobia (57/172, 33.1%) or with nausea, photophobia and phonophobia (92/172, 53.5%) and presented high sensitivity (86.0%, 95% CI 80.2-90.3) and specificity (94.0%, 95% CI 89.5-96.7), with low percentages of false positives (6.5%, 95% CI 3.6-11.4) and negatives (13.0%, 95% CI 8.9-18.4). In the period between attacks, osmophobia was restricted to migraine patients (48/200, 24.0%). The areas under ROC curves were: 0.903 ± 0.017 to osmophobia during crisis; 0.784 ± 0.025 between crises; 0.807 ± 0.023 to photophobia/phonophobia, and 0.885 ± 0.017 to pain developed by odors. Osmophobia may be a specific marker to differentiate migraine from tension-type headache, which suggests its inclusion within the criteria to diagnose migraine.