title: Head or neck injury increases the risk of chronic daily headache: a population-based study.
abstract: OBJECTIVE
  To evaluate the extent to which head and neck injury (HANI) contributes to chronic daily headache (CDH).
  
  
  BACKGROUND
  In prospective studies, head injury is associated with headache (HA) that remains a problem at 12 to 24 months post-head injury in 20 to 30% of patients. Of these, up to 30 to 50% manifest CDH. The degree to which head injury contributes to CDH has not been evaluated in a non-clinical population. We evaluate the relationship between lifetime occurrence of HANI and CDH in a randomly chosen population sample.
  
  
  METHODS
  Study participants are from the Frequent Headache Epidemiology Study. Cases with CDH (> or =180 HA/year) and a comparison group with episodic headache (EH, 2 to 102 HA/year) were identified from the general population. Subjects were asked about lifetime occurrence of HANI. HANI were further classified as potentially precipitating injuries (PPI) if they occurred within 2 years of CDH onset for cases or in an equivalent 2-year period for EH controls.
  
  
  RESULTS
  Lifetime occurrence of HANI was more frequent in cases than controls for men (adjusted OR = 3.1 [1.3 to 7.2]), women (OR = 1.5 [0.97 to 2.3]), and overall (OR = 1.7 [1.1 to 2.4]). The attributable risk was 15% (36% men, 11% women). Results were similar for PPI. The odds of CDH increased with the number of lifetime HANI in all groups (p < 0.05 trend).
  
  
  CONCLUSIONS
  Results suggest that head and neck injury (HANI) accounts for approximately 15% of chronic daily headache (CDH) cases in this non-clinical population. The relationship between HANI and CDH was not limited to injuries proximate to CDH onset. The lifetime risk of CDH increases with increasing number of HANI.
authors.affiliation: Department of Neurology, University of Oklahoma Medical School, Oklahoma City, OK 73104, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Couch
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lipton
authors.forename: Walter F
authors.initials: WF
authors.lastname: Stewart
authors.forename: Ann I
authors.initials: AI
authors.lastname: Scher
mesh_terms: D000328:Adult; D017677:Age Distribution; D015331:Cohort Studies; D015897:Comorbidity; D006259:Craniocerebral Trauma / Q000453:epidemiology*; D005260:Female; D020773:Headache Disorders / Q000453:epidemiology*; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D020325:Migraine with Aura / Q000453:epidemiology; D019838:Neck Injuries / Q000453:epidemiology*; D012307:Risk Factors; D017678:Sex Distribution; D018781:Tension-Type Headache / Q000453:epidemiology; D014481:United States / Q000453:epidemiology