title: Impact of comorbidity on headache-related disability.
abstract: OBJECTIVE
  To assess and compare the extent to which comorbid conditions explain the role disability associated with migraine and other severe headaches.
  
  
  METHODS
  A probability sample of US adults (n = 5,692) was interviewed. Presence of headaches, other chronic pain conditions, and chronic physical conditions was assessed in a structured interview administered by trained interviewers. Diagnostic criteria for migraine were based on the International Headache Society classification. Mental disorders were ascertained with the Composite International Diagnostic Interview that collected diagnostic criteria according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition. Role disability was assessed with World Health Organization Disability Assessment Schedule questions about days out of role and days with impaired role functioning.
  
  
  RESULTS
  Eighty-three percent of migraineurs and 79% of persons with other severe types of headache had some form of comorbidity. Compared with headache-free subjects, migraineurs were at significantly increased risk for mental disorders (odds ratio [OR] 3.1), other pain conditions (OR 3.3), and physical diseases (OR 2.1). Compared with headache-free subjects, persons with nonmigraine headache were also at significantly increased risk for mental disorders (OR 2.0), other pain conditions (OR 3.5), and physical diseases (OR 1.7). Migraineurs experienced role disability on 25.2% of the last 30 days compared with 17.6% of the days for persons with nonmigraine headaches and 9.7% of the days for persons without headache. Comorbid conditions explained 65% of the role disability associated with migraine and all of the role disability associated with other severe headaches.
  
  
  CONCLUSIONS
  Comorbidity is an important factor in understanding disability among persons with headache.
authors.affiliation: Center for Health Studies, Group Health Cooperative, 1730 Minor Ave., Suite 1600, Seattle, WA 98101, USA. saunders.k@ghc.org
authors.forename: K
authors.initials: K
authors.lastname: Saunders
authors.forename: K
authors.initials: K
authors.lastname: Merikangas
authors.forename: N C P
authors.initials: NC
authors.lastname: Low
authors.forename: M
authors.initials: M
authors.lastname: Von Korff
authors.forename: R C
authors.initials: RC
authors.lastname: Kessler
mesh_terms: D000203:Activities of Daily Living / Q000523:psychology; D000293:Adolescent; D000328:Adult; D002908:Chronic Disease / Q000453:epidemiology; D015897:Comorbidity; D017281:Cost of Illness; D003625:Data Collection; D004185:Disability Evaluation; D005260:Female; D020773:Headache Disorders / Q000453:epidemiology*; D006801:Humans; D008297:Male; D001523:Mental Disorders / Q000453:epidemiology; D008875:Middle Aged; D008881:Migraine Disorders / Q000453:epidemiology; D010148:Intractable Pain / Q000453:epidemiology; D015995:Prevalence; D014481:United States / Q000453:epidemiology