title: Prevalence of medication overuse headache in an interdisciplinary pain clinic.
abstract: BACKGROUND
  Medication overuse headache (MOH) has been recognized as an important problem in headache patients although the pathophysiological mechanisms remain unclear. The diagnosis of MOH is based on clinical characteristics defined by the International Headache Society. The aim was the evaluation of the diagnostic criteria of MOH in a mixed population of chronic pain patients to gain information about the prevalence and possible associations with MOH.
  
  
  METHODS
  Data of all patients referred to the interdisciplinary pain clinic at the University Hospital of Zurich between September 2005 and December 2007 were retrospectively analyzed. Demographic data (age, sex, history of migration), as well as data about duration of pain disease, category of pain disease (neurological, psychiatric, rheumatologic, other), use of medication, history of trauma, and comorbidity of depression and anxiety have been collected.
  
  
  RESULTS
  Totally 178 of 187 consecutive chronic pain patients were included in the study. A total of 138 patients (78%) used analgesics on 15 or more days per month. Chronic headache was more prevalent among patients with analgesic overuse (39.8%) than without analgesic overuse (18%). The prevalence of MOH was 29%. The odds ratio (OR) for a patient with medication overuse to have chronic headache was 13.1 if he had a history of primary headache, compared to a patient without a primary headache syndrome. Furthermore, history of headache (OR 2.5, CI [1.13;5.44]), history of migration (OR 2.9, CI [1.31;6.32]) and comorbid depression (OR 3.5, CI [1.46;8.52]) were associated with overuse of acute medication, in general.
  
  
  CONCLUSIONS
  Primary headaches have a high risk for chronification in patients overusing analgesics for other pain disorders. Whereas history of headache, history of migration and comorbidity of depression are independentely associated with analgesic overuse in this group of patients.
authors.affiliation: Institute of Anesthesiology, University Hospital of Zurich, Rämistrasse 100, Zurich 8091, Switzerland.
authors.forename: Corinne Wanner
authors.initials: CW
authors.lastname: Schmid
authors.forename: Konrad
authors.initials: K
authors.lastname: Maurer
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Schmid
authors.forename: Eli
authors.initials: E
authors.lastname: Alon
authors.forename: Donat R
authors.initials: DR
authors.lastname: Spahn
authors.forename: Andreas R
authors.initials: AR
authors.lastname: Gantenbein
authors.forename: Peter S
authors.initials: PS
authors.lastname: Sandor
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000700:Analgesics / Q000009:adverse effects*; D015897:Comorbidity; D003863:Depression / Q000453:epidemiology; D005260:Female; D051271:Headache Disorders, Secondary / Q000139:chemically induced* / Q000453:epidemiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology; D018710:Pain Clinics; D015995:Prevalence; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000700:Analgesics
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