title: Differences in Clinical Features and Disability according to the Frequency of Medication Use in Patients with Chronic Migraine.
abstract: OBJECTIVE
  Chronic migraine (CM) has a significant impact on daily activities, and analgesic overuse is a major contributing factor to migraine transformation. Limited information is available on the functional consequences of CM stemming from analgesic overuse. This study evaluated the impact of the frequency of analgesic medication use on headache-related disability and clinical features in patients with CM.
  
  
  METHODS
  PATIENTS WITH CM WERE ENROLLED CONSECUTIVELY AND CLASSIFIED INTO TWO GROUPS ACCORDING TO THEIR FREQUENCY OF MEDICATION USE: <15 days/month (CM-ML, n=52) and ≥15 days/month (CM-MH, n=68). All patients completed a structured questionnaire concerning the clinical features of their migraine, a validated version of the Migraine Disability Assessment questionnaire (MIDAS), and the Headache Impact Test-6 (HIT-6).
  
  
  RESULTS
  The pain intensity, as measured by a visual analog scale, was greater in the CM-MH group than in the CM-ML group (8.5±0.2 vs. 7.7±0.3, mean±SD; p<0.05). In the disability domain, the MIDAS scores were significantly higher for CM-MH patients than for CM-ML patients (47.6±4.8 vs. 26.8±4.5, p<0.01). The impact from migraine, as measured by the HIT-6, was greater for CM-MH patients than for CM-ML patients (65.6±1.0 vs. 62.1±1.0, p<0.05).
  
  
  CONCLUSIONS
  Our results indicate that the headache pain intensity and disability are greater in patients with CM who use medication frequently.
authors.affiliation: Department of Neurology, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea.
authors.forename: Gyoung Im
authors.initials: GI
authors.lastname: Suh
authors.forename: Jeong Wook
authors.initials: JW
authors.lastname: Park
authors.forename: Hae Eun
authors.initials: HE
authors.lastname: Shin
keywords: HIT-6; MIDAS; chronic migraine; disability; medication overuse