Results of a Population-Based Case-Control and Case-Crossover Study
J. David Cassidy, DC, PhD
Journal of Manipulative and Physiological Therapeutics
Volume 32, Issue 2, Supplement , Pages S201-S208, February 2009
Abstract
Study Design
Population-based, case-control and case-crossover study.
Objective
To investigate associations between chiropractic visits and vertebrobasilar artery (VBA) stroke and to contrast this with primary care physician (PCP) visits and VBA stroke.
Summary of Background Data
Chiropractic care is popular for neck pain and headache, but may increase the risk for VBA dissection and stroke. Neck pain and headache are common symptoms of VBA dissection, which commonly precedes VBA stroke.
Methods
Cases included eligible incident VBA strokes admitted to Ontario hospitals from April 1, 1993 to March 31, 2002. Four controls were age and gender matched to each case. Case and control exposures to chiropractors and PCPs were determined from health billing records in the year before the stroke date. In the case-crossover analysis, cases acted as their own controls.
Results
There were 818 VBA strokes hospitalized in a population of more than 100 million person-years. In those aged
Conclusion
VBA stroke is a very rare event in the population. The increased risks of VBA stroke associated with chiropractic and PCP visits is likely due to patients with headache and neck pain from VBA dissection seeking care before their stroke. We found no evidence of excess risk of VBA stroke associated chiropractic care compared to primary care.