Chiropractic Manipulation Not Associated With VBA Stroke
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- Spinal Manipulative Therapy (SMT) has been accused of causing vertebrobasilar dissection (VBD) and stroke. In his Ontario study, Cassidy found an association between VBD and chiropractor visits, but the association was identical to the association between VBD and primary care provider (PCP) visits. This led to the conclusion that there was no causal relationship between SMT and VBD. It was determined that patients with a VBD in progress and went to a chiropractor or a primary care provider for neck pain and headache.
- This study evaluates the vertebrobasilar stroke (VBS) incidence for 14.7 million people over three years. This study is 5 times larger than the Cassidy study.
- In its results, this study found no significant association between chiropractic office visits and VBS. There was an association between VBS and PCP visits. This association is assumed to be in relation to patients seeking care for a VBS in progress and not causative.
Abstract
Background
There is controversy surrounding the risk of manipulation, which is often used by chiropractors, with respect to its association with vertebrobasilar artery system (VBA) stroke. The objective of this study was to compare the associations between chiropractic care and VBA stroke with recent primary care physician (PCP) care and VBA stroke.
Methods
The study design was a case–control study of commercially insured and Medicare Advantage (MA) health plan members in the U.S. population between January 1, 2011 and December 31, 2013. Administrative data were used to identify exposures to chiropractic and PCP care. Separate analyses using conditional logistic regression were conducted for the commercially insured and the MA populations. The analysis of the commercial population was further stratified by age (<45 years; ≥45 years). Odds ratios were calculated to measure associations for different hazard periods. A secondary descriptive analysis was conducted to determine the relevance of using chiropractic visits as a proxy for exposure to manipulative treatment.
Results
There were a total of 1,829 VBA stroke cases (1,159 – commercial; 670 – MA). The findings showed no significant association between chiropractic visits and VBA stroke for either population or for samples stratified by age. In both commercial and MA populations, there was a significant association between PCP visits and VBA stroke incidence regardless of length of hazard period. The results were similar for age-stratified samples. The findings of the secondary analysis showed that chiropractic visits did not report the inclusion of manipulation in almost one third of stroke cases in the commercial population and in only 1 of 2 cases of the MA cohort.
Conclusions
We found no significant association between exposure to chiropractic care and the risk of VBA stroke. We conclude that manipulation is an unlikely cause of VBA stroke. The positive association between PCP visits and VBA stroke is most likely due to patient decisions to seek care for the symptoms (headache and neck pain) of arterial dissection. We further conclude that using chiropractic visits as a measure of exposure to manipulation may result in unreliable estimates of the strength of association with the occurrence of VBA stroke.
Citation
(open Access)