title: Problem with defining headache etiology using patient symptomatology.
authors: Departments of Biostatistics and Epidemiology, Anesthesiology, and Neurology, University of Pennsylvania, Philadelphia, PA, USA.
authors: John T
authors: JT
authors: Farrar
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D008881:Migraine Disorders / Q000145:classification* / Q000175:diagnosis*; D012720:Severity of Illness Index; D018781:Tension-Type Headache / Q000145:classification* / Q000175:diagnosis*