By Shawn Neff

Editorial Review

Risk of Carotid Stroke after Chiropractic Care: A Population-Based Case-Crossover Study

J. David Cassidy, DC, PhD, DrMedSc, Eleanor Boyle, PhD, Pierre Côté, DC, PhD, Sheilah Hogg-Johnson, PhD, Susan J. Bondy, PhD, and Scott Haldeman, MD, PhD

Journal of Stroke and Cerebrovascular Diseases, Vol. 26, No. 4 (April), 2017: pp 842–850

JACO Editorial Reviewer: Jaroslaw P. Grod, D.C., FCCS(C)

Published: June 2018
Journal of the Academy of Chiropractic Orthopedists
June 2018, Volume 15, Issue 2

The original article copyright belongs to the original publisher. This review is available from: http://www.dcorthoacademy.com

© 2018 Grod and the Academy of Chiropractic Orthopedists. This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors’ Abstract:

Background: Chiropractic manipulation is a popular treatment for neck pain and headache, but may increase the risk of cervical artery dissection and stroke. Patients with carotid artery dissection can present with neck pain and/or headache before experiencing a stroke. These are common symptoms seen by both chiropractors and primary care physicians (PCPs). We aimed to assess the risk of carotid artery stroke after chiropractic care by comparing association between chiropractic and PCP visits and subsequent stroke. Methods: A population-based, case-crossover study was undertaken in Ontario, Canada. All incident cases of carotid artery stroke admitted to hospitals over a 9-year period were identified. Cases served as their own controls. Exposures to chiropractic and PCP services were determined from health billing records. Results: We compared 15,523 cases to 62,092 control periods using exposure windows of 1, 3, 7, and 14 days prior to the stroke. Positive associations were found for both chiropractic and PCP visits and subsequent stroke in patients less than 45 years of age. These associations tended to increase when analyses were limited to visits for neck pain and headache-related diagnoses. There was no significant difference between chiropractic and PCP risk estimates. We found no association between chiropractic visits and stroke in those 45 years of age or older. Conclusions: We found no excess risk of carotid artery stroke after chiropractic care. Associations between chiropractic and PCP visits and stroke were similar and likely due to patients with early dissection-related symptoms seeking care prior to developing their strokes. Key Words: Stroke—stroke prevention—risk factor—spinal manipulation. © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

JACO Editorial Summary:

This article was written by authors from the following institutions:
From the *Department of Sports Science and Clinical Biomechanics, Faculty of Health, University of Southern Denmark, Odense, Denmark; †Division of Health Care and Outcomes Research, Krembil Research Institute, University Health Network, Toronto, Ontario, Canada; ‡Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; §Faculty of Health Sciences, University of Ontario Institute of Technology and UOIT-CMCC Centre for Disability Prevention and Rehabilitation, Oshawa, Ontario, Canada; ‖Institute for Work and Health, Toronto, Ontario, Canada; ¶Division of Biostatistics, Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada; and #Department of Neurology, University of California, Irvine, California.

Chiropractic manipulation is a popular treatment for neck pain and headache but may increase the risk of cervical artery dissection and stroke.
These are common symptoms seen by both chiropractors and primary care physicians (PCPs).
The study aimed to assess the risk of carotid artery stroke after chiropractic care by comparing association between chiropractic and PCP visits and subsequent stroke.
This was a population-based, case-crossover study that was undertaken in Ontario, Canada.
All incident cases of carotid artery stroke admitted to hospitals over a 9-year period were identified.
The study compared 15,523 cases to 62,092 control periods using exposure windows of 1, 3, 7, and 14 days prior to the stroke.
They found no association between chiropractic visits and stroke in those 45 years of age or older.
Summary:

Associations between chiropractic and PCP visits and stroke were similar and likely due to patients with early dissection-related symptoms seeking care prior to developing their strokes.

They used a time-stratified approach, 4 control periods were randomly chosen during the year prior to the stroke for each case.

This is the first population-based controlled study to address the risk of carotid artery strokes after chiropractic care.

Headache and neck pain are common presenting symptoms in patients with cervical artery dissection and in some cases are the only presenting symptoms. They are also common and recurrent in the general population. Although some ischemic events are preceded by sudden intense neck and/or head pain, in many cases it is less sudden and severe and likely indistinguishable from less serious causes.

This study base includes the entire population of Ontario, Canada, over a 9-year period, representing 109,020,875 person-years of observation, and the results should be generalizable to other populations where chiropractic treatment is offered.

The conclusion of the study suggests that the association between chiropractic care and carotid artery stroke could be due to care being delivered for dissection-related neck pain and/or headache, prior to the ischemic event.