title: Migraine headache and ischemic stroke risk: an updated meta-analysis.
abstract: BACKGROUND
  Observational studies, including recent large cohort studies that were unavailable for prior meta-analysis, have suggested an association between migraine headache and ischemic stroke. We performed an updated meta-analysis to quantitatively summarize the strength of association between migraine and ischemic stroke risk.
  
  
  METHODS
  We systematically searched electronic databases, including MEDLINE and EMBASE, through February 2009 for studies of human subjects in the English language. Study selection using a priori selection criteria, data extraction, and assessment of study quality were conducted independently by reviewer pairs using standardized forms.
  
  
  RESULTS
  Twenty-one (60%) of 35 studies met the selection criteria, for a total of 622,381 participants (13 case-control, 8 cohort studies) included in the meta-analysis. The pooled adjusted odds ratio of ischemic stroke comparing migraineurs with nonmigraineurs using a random effects model was 2.30 (95% confidence interval [CI], 1.91-2.76). The pooled adjusted effect estimates for studies that reported relative risks and hazard ratios, respectively, were 2.41 (95% CI, 1.81-3.20) and 1.52 (95% CI, 0.99-2.35). The overall pooled effect estimate was 2.04 (95% CI, 1.72-2.43). Results were robust to sensitivity analyses excluding lower quality studies.
  
  
  CONCLUSIONS
  Migraine is associated with increased ischemic stroke risk. These findings underscore the importance of identifying high-risk migraineurs with other modifiable stroke risk factors. Future studies of the effect of migraine treatment and modifiable risk factor reduction on stroke risk in migraineurs are warranted.
authors.affiliation: Johns Hopkins University Bloomberg School of Public Health, Baltimore, Md, USA.
authors.forename: June T
authors.initials: JT
authors.lastname: Spector
authors.forename: Susan R
authors.initials: SR
authors.lastname: Kahn
authors.forename: Miranda R
authors.initials: MR
authors.lastname: Jones
authors.forename: Monisha
authors.initials: M
authors.lastname: Jayakumar
authors.forename: Deepan
authors.initials: D
authors.lastname: Dalal
authors.forename: Saman
authors.initials: S
authors.lastname: Nazarian
mesh_terms: D006801:Humans; D008881:Migraine Disorders / Q000150:complications*; D016017:Odds Ratio; D012307:Risk Factors; D020521:Stroke / Q000209:etiology*