title: Systematic Review and Meta-analysis of Chiropractic Care and Cervical Artery Dissection: No Evidence for Causation.
abstract: BACKGROUND
  Case reports and case control studies have suggested an association between chiropractic neck manipulation and cervical artery dissection (CAD), but a causal relationship has not been established. We evaluated the evidence related to this topic by performing a systematic review and meta-analysis of published data on chiropractic manipulation and CAD.
  
  
  METHODS
  Search terms were entered into standard search engines in a systematic fashion. The articles were reviewed by study authors, graded independently for class of evidence, and combined in a meta-analysis. The total body of evidence was evaluated according to GRADE criteria.
  
  
  RESULTS
  Our search yielded 253 articles. We identified two class II and four class III studies. There were no discrepancies among article ratings (i.e., kappa=1). The meta-analysis revealed a small association between chiropractic care and dissection (OR 1.74, 95% CI 1.26-2.41). The quality of the body of evidence according to GRADE criteria was "very low."
  
  
  CONCLUSIONS
  The quality of the published literature on the relationship between chiropractic manipulation and CAD is very low. Our analysis shows a small association between chiropractic neck manipulation and cervical artery dissection. This relationship may be explained by the high risk of bias and confounding in the available studies, and in particular by the known association of neck pain with CAD and with chiropractic manipulation. There is no convincing evidence to support a causal link between chiropractic manipulation and CAD. Belief in a causal link may have significant negative consequences such as numerous episodes of litigation.
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Ephraim W
authors.initials: EW
authors.lastname: Church
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Emily P
authors.initials: EP
authors.lastname: Sieg
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Omar
authors.initials: O
authors.lastname: Zalatimo
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Namath S
authors.initials: NS
authors.lastname: Hussain
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Michael
authors.initials: M
authors.lastname: Glantz
authors.affiliation: Department of Neurosurgery, Penn State Hershey Medical Center.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Harbaugh
keywords: cervical artery dissection; cervical manipulation; cervical spine manipulative therapy; chiropractic manipulation; internal carotid artery dissection; vertebral atery dissection